HDOJ 4888 Redraw Beautiful Drawings && HDOJ 4975 A simple Gaussian elimination problem

解题思路：

这两道题题目大致相同，都是已知一个矩阵每一行的和和每一列的和，并且每个点的数小于K  还原原矩阵并判断答案是否唯一。建图方式相同，新建一个原点S 和一个汇点T ，S到行连边，容量为该行之和，列到T连边，容量为该列之和， 对于每一个点 i 和 j ，i 行向 j 列连边 ， 容量为K , 求一遍最大流。并且通过判断是否存在环来判断是否唯一。

区别在于 第二道题N 与 M 均扩大，找环需要采用更高效的算法，这里采用Tarjan 算法来找环。

HDOJ 4888

#include <iostream>#include <cstring>#include <cstdlib>#include <cstdio>#include <algorithm>#include <cmath>#include <vector>#include <queue>#include <stack>#define LL long longusing namespace std;const int maxn = 10000 + 10;const int INF = 100000000;struct Edge{    int from,to,cap,flow;    Edge(int u,int v,int c,int w):from(u),to(v),cap(c),flow(w){ }};int n , s , t;vector<Edge> edges;vector<int> G[maxn];bool vis[maxn];int d[maxn];int cur[maxn];void init(){    for(int i=0;i<=n+1;i++)        G[i].clear();    edges.clear();}void AddEdge(int from,int to,int cap){    edges.push_back(Edge(from,to,cap,0));    edges.push_back(Edge(to,from,0,0));    int M = edges.size();    G[from].push_back(M-2);    G[to].push_back(M-1);}bool BFS(){    memset(vis,0,sizeof(vis));    queue<int>Q;    Q.push(s);    d[s] = 0;    vis[s] = 1;    while(!Q.empty())    {        int x = Q.front();Q.pop();        for(int i=0;i<G[x].size();i++)        {            Edge& e = edges[G[x][i]];            if(!vis[e.to] && e.cap > e.flow)            {                vis[e.to] = 1;                d[e.to] = d[x] + 1;                Q.push(e.to);            }        }    }    return vis[t];}int DFS(int x,int a){    if(x == t || a == 0) return a;    int flow = 0 , f;    for(int &i = cur[x];i<G[x].size();i++)    {        Edge& e = edges[G[x][i]];        if(d[x] + 1 == d[e.to] && (f = DFS(e.to,min(a,e.cap-e.flow))) > 0)        {            e.flow += f;            edges[G[x][i]^1].flow -= f;            flow += f;            a -= f;            if(a == 0) break;        }    }    return flow;}int Maxflow(){    int flow = 0;    while(BFS())    {        memset(cur,0,sizeof(cur));        flow += DFS(s,INF);    }    return flow;}int pre[maxn] , lowlink[maxn] ,sccno[maxn] , fa[maxn], dfs_clock , scc_cnt , flag;stack<int> S;void dfs(int u){    pre[u] = lowlink[u] = ++dfs_clock;    S.push(u);    for(int i=0;i<G[u].size();i++)    {        Edge& e = edges[G[u][i]];        if(e.cap == e.flow) continue;        int v = e.to;        if(!pre[v])        {            fa[v] = u;            dfs(v);            if(!flag) return ;            lowlink[u] = min(lowlink[u] , lowlink[v]);        }        else if(!sccno[v])        {         lowlink[u] = min(lowlink[u] , pre[v]);         if(v != fa[u]) {flag = 0 ; return ;}        }    }    if(lowlink[u] == pre[u])    {        scc_cnt++;        for(;;)        {            int x = S.top(); S.pop();            sccno[x] = scc_cnt;            if(x == u) break;        }    }}bool find_scc(){    dfs_clock = scc_cnt = 0; flag = 1;    memset(pre , 0, sizeof(pre));    memset(lowlink , 0, sizeof(lowlink));    memset(sccno , 0 , sizeof(sccno));    for(int i=0;i<n;i++)    if(!pre[i]) { dfs(i); if(!flag) return 0;}    return 1;}int main(){    int T;    int N , M , K;    while(scanf("%d%d%d",&N,&M,&K)!=EOF)    {s = 0 , t = N + M + 1;        n = t + 1; init();        int sumr = 0 , sumc = 0;        int x;        for(int i=1;i<=N;i++)        {            scanf("%d",&x);            AddEdge(s , i , x);            sumr += x;        }        for(int i=1;i<=M;i++)        {            scanf("%d",&x);            AddEdge(i + N , t , x);            sumc += x;        }if (sumr != sumc){ printf("Impossible\n");continue; }        for(int i=1;i<=N;i++)        {            for(int j=1;j<=M;j++)            {                AddEdge(i , j + N , K);            }        }        int ans = Maxflow();        if(ans != sumr) { printf("Impossible\n"); continue; }        if(find_scc()){printf("Unique\n");for(int i=1;i<=N;i++){for(int j=1;j<=M;j++){Edge& e = edges[G[i][j]];    cout<<e.flow;    if(j < M) cout<<' ';}cout<<endl;}}        else printf("Not Unique\n");    }    return 0;}

HDOJ 4975 

<span style="color:#0000ff;">#include <iostream>#include <cstring>#include <cstdlib>#include <cstdio>#include <algorithm>#include <cmath>#include <vector>#include <queue>#include <stack>#define LL long long</span><strong><span style="color:#0000ff;">using namespace</span></strong> std<strong><span style="color:#ff00ff;">;</span><span style="color:#0000ff;">const</span><span style="color:blue;"> int</span></strong> maxn<strong><span style="color:#ff00ff;"> =</span></strong><span style="color:#cc3300;"> 10000</span><strong><span style="color:#ff00ff;"> +</span></strong><span style="color:#cc3300;"> 10</span><strong><span style="color:#ff00ff;">;</span><span style="color:#0000ff;">const</span><span style="color:blue;"> int</span></strong> INF<strong><span style="color:#ff00ff;"> =</span></strong><span style="color:#cc3300;"> 100000000</span><strong><span style="color:#ff00ff;">;</span><span style="color:#0000ff;">struct</span></strong> Edge<strong><span style="color:#ff00ff;">{</span><span style="color:blue;">    int</span></strong> from<strong><span style="color:#ff00ff;">,</span></strong>to<strong><span style="color:#ff00ff;">,</span></strong>cap<strong><span style="color:#ff00ff;">,</span></strong>flow<strong><span style="color:#ff00ff;">;</span></strong>    Edge<strong><span style="color:#ff00ff;">(</span><span style="color:blue;">int</span></strong> u<strong><span style="color:#ff00ff;">,</span><span style="color:blue;">int</span></strong> v<strong><span style="color:#ff00ff;">,</span><span style="color:blue;">int</span></strong> c<strong><span style="color:#ff00ff;">,</span><span style="color:blue;">int</span></strong> w<strong><span style="color:#ff00ff;">):</span></strong>from<strong><span style="color:#ff00ff;">(</span></strong>u<strong><span style="color:#ff00ff;">),</span></strong>to<strong><span style="color:#ff00ff;">(</span></strong>v<strong><span style="color:#ff00ff;">),</span></strong>cap<strong><span style="color:#ff00ff;">(</span></strong>c<strong><span style="color:#ff00ff;">),</span></strong>flow<strong><span style="color:#ff00ff;">(</span></strong>w<strong><span style="color:#ff00ff;">){ }};</span><span style="color:blue;">int</span></strong> n<strong><span style="color:#ff00ff;"> ,</span></strong> s<strong><span style="color:#ff00ff;"> ,</span></strong> t<strong><span style="color:#ff00ff;">;</span></strong>vector<strong><span style="color:#ff00ff;"><</span></strong>Edge<strong><span style="color:#ff00ff;">></span></strong> edges<strong><span style="color:#ff00ff;">;</span></strong>vector<strong><span style="color:#ff00ff;"><</span><span style="color:blue;">int</span><span style="color:#ff00ff;">></span></strong> G<strong><span style="color:#ff00ff;">[</span></strong>maxn<strong><span style="color:#ff00ff;">];</span><span style="color:blue;">bool</span></strong> vis<strong><span style="color:#ff00ff;">[</span></strong>maxn<strong><span style="color:#ff00ff;">];</span><span style="color:blue;">int</span></strong> d<strong><span style="color:#ff00ff;">[</span></strong>maxn<strong><span style="color:#ff00ff;">];</span><span style="color:blue;">int</span></strong> cur<strong><span style="color:#ff00ff;">[</span></strong>maxn<strong><span style="color:#ff00ff;">];</span><span style="color:blue;">void</span></strong> init<strong><span style="color:#ff00ff;">(){</span><span style="color:#0000ff;">    for</span><span style="color:#ff00ff;">(</span><span style="color:blue;">int</span></strong> i<strong><span style="color:#ff00ff;">=</span></strong><span style="color:#cc3300;">0</span><strong><span style="color:#ff00ff;">;</span></strong>i<strong><span style="color:#ff00ff;"><=</span></strong>n<strong><span style="color:#ff00ff;">+</span></strong><span style="color:#cc3300;">1</span><strong><span style="color:#ff00ff;">;</span></strong>i<strong><span style="color:#ff00ff;">++)</span></strong>        G<strong><span style="color:#ff00ff;">[</span></strong>i<strong><span style="color:#ff00ff;">].</span></strong>clear<strong><span style="color:#ff00ff;">();</span></strong>    edges<strong><span style="color:#ff00ff;">.</span></strong>clear<strong><span style="color:#ff00ff;">();}</span><span style="color:blue;">void</span></strong> AddEdge<strong><span style="color:#ff00ff;">(</span><span style="color:blue;">int</span></strong> from<strong><span style="color:#ff00ff;">,</span><span style="color:blue;">int</span></strong> to<strong><span style="color:#ff00ff;">,</span><span style="color:blue;">int</span></strong> cap<strong><span style="color:#ff00ff;">){</span></strong>    edges<strong><span style="color:#ff00ff;">.</span></strong>push_back<strong><span style="color:#ff00ff;">(</span></strong>Edge<strong><span style="color:#ff00ff;">(</span></strong>from<strong><span style="color:#ff00ff;">,</span></strong>to<strong><span style="color:#ff00ff;">,</span></strong>cap<strong><span style="color:#ff00ff;">,</span></strong><span style="color:#cc3300;">0</span><strong><span style="color:#ff00ff;">));</span></strong>    edges<strong><span style="color:#ff00ff;">.</span></strong>push_back<strong><span style="color:#ff00ff;">(</span></strong>Edge<strong><span style="color:#ff00ff;">(</span></strong>to<strong><span style="color:#ff00ff;">,</span></strong>from<strong><span style="color:#ff00ff;">,</span></strong><span style="color:#cc3300;">0</span><strong><span style="color:#ff00ff;">,</span></strong><span style="color:#cc3300;">0</span><strong><span style="color:#ff00ff;">));</span><span style="color:blue;">    int</span></strong> M<strong><span style="color:#ff00ff;"> =</span></strong> edges<strong><span style="color:#ff00ff;">.</span></strong>size<strong><span style="color:#ff00ff;">();</span></strong>    G<strong><span style="color:#ff00ff;">[</span></strong>from<strong><span style="color:#ff00ff;">].</span></strong>push_back<strong><span style="color:#ff00ff;">(</span></strong>M<strong><span style="color:#ff00ff;">-</span></strong><span style="color:#cc3300;">2</span><strong><span style="color:#ff00ff;">);</span></strong>    G<strong><span style="color:#ff00ff;">[</span></strong>to<strong><span style="color:#ff00ff;">].</span></strong>push_back<strong><span style="color:#ff00ff;">(</span></strong>M<strong><span style="color:#ff00ff;">-</span></strong><span style="color:#cc3300;">1</span><strong><span style="color:#ff00ff;">);}</span><span style="color:blue;">bool</span></strong> BFS<strong><span style="color:#ff00ff;">(){</span></strong>    memset<strong><span style="color:#ff00ff;">(</span></strong>vis<strong><span style="color:#ff00ff;">,</span></strong><span style="color:#cc3300;">0</span><strong><span style="color:#ff00ff;">,</span><span style="color:#0000ff;">sizeof</span><span style="color:#ff00ff;">(</span></strong>vis<strong><span style="color:#ff00ff;">));</span></strong>    queue<strong><span style="color:#ff00ff;"><</span><span style="color:blue;">int</span><span style="color:#ff00ff;">></span></strong>Q<strong><span style="color:#ff00ff;">;</span></strong>    Q<strong><span style="color:#ff00ff;">.</span></strong>push<strong><span style="color:#ff00ff;">(</span></strong>s<strong><span style="color:#ff00ff;">);</span></strong>    d<strong><span style="color:#ff00ff;">[</span></strong>s<strong><span style="color:#ff00ff;">] =</span></strong><span style="color:#cc3300;"> 0</span><strong><span style="color:#ff00ff;">;</span></strong>    vis<strong><span style="color:#ff00ff;">[</span></strong>s<strong><span style="color:#ff00ff;">] =</span></strong><span style="color:#cc3300;"> 1</span><strong><span style="color:#ff00ff;">;</span><span style="color:#0000ff;">    while</span><span style="color:#ff00ff;">(!</span></strong>Q<strong><span style="color:#ff00ff;">.</span></strong>empty<strong><span style="color:#ff00ff;">())    {</span><span style="color:blue;">        int</span></strong> x<strong><span style="color:#ff00ff;"> =</span></strong> Q<strong><span style="color:#ff00ff;">.</span></strong>front<strong><span style="color:#ff00ff;">();</span></strong>Q<strong><span style="color:#ff00ff;">.</span></strong>pop<strong><span style="color:#ff00ff;">();</span><span style="color:#0000ff;">        for</span><span style="color:#ff00ff;">(</span><span style="color:blue;">int</span></strong> i<strong><span style="color:#ff00ff;">=</span></strong><span style="color:#cc3300;">0</span><strong><span style="color:#ff00ff;">;</span></strong>i<strong><span style="color:#ff00ff;"><</span></strong>G<strong><span style="color:#ff00ff;">[</span></strong>x<strong><span style="color:#ff00ff;">].</span></strong>size<strong><span style="color:#ff00ff;">();</span></strong>i<strong><span style="color:#ff00ff;">++)        {</span></strong>            Edge<strong><span style="color:#ff00ff;">&</span></strong> e<strong><span style="color:#ff00ff;"> =</span></strong> edges<strong><span style="color:#ff00ff;">[</span></strong>G<strong><span style="color:#ff00ff;">[</span></strong>x<strong><span style="color:#ff00ff;">][</span></strong>i<strong><span style="color:#ff00ff;">]];</span><span style="color:#0000ff;">            if</span><span style="color:#ff00ff;">(!</span></strong>vis<strong><span style="color:#ff00ff;">[</span></strong>e<strong><span style="color:#ff00ff;">.</span></strong>to<strong><span style="color:#ff00ff;">] &&</span></strong> e<strong><span style="color:#ff00ff;">.</span></strong>cap<strong><span style="color:#ff00ff;"> ></span></strong> e<strong><span style="color:#ff00ff;">.</span></strong>flow<strong><span style="color:#ff00ff;">)            {</span></strong>                vis<strong><span style="color:#ff00ff;">[</span></strong>e<strong><span style="color:#ff00ff;">.</span></strong>to<strong><span style="color:#ff00ff;">] =</span></strong><span style="color:#cc3300;"> 1</span><strong><span style="color:#ff00ff;">;</span></strong>                d<strong><span style="color:#ff00ff;">[</span></strong>e<strong><span style="color:#ff00ff;">.</span></strong>to<strong><span style="color:#ff00ff;">] =</span></strong> d<strong><span style="color:#ff00ff;">[</span></strong>x<strong><span style="color:#ff00ff;">] +</span></strong><span style="color:#cc3300;"> 1</span><strong><span style="color:#ff00ff;">;</span></strong>                Q<strong><span style="color:#ff00ff;">.</span></strong>push<strong><span style="color:#ff00ff;">(</span></strong>e<strong><span style="color:#ff00ff;">.</span></strong>to<strong><span style="color:#ff00ff;">);            }        }    }</span><span style="color:#0000ff;">    return</span></strong> vis<strong><span style="color:#ff00ff;">[</span></strong>t<strong><span style="color:#ff00ff;">];}</span><span style="color:blue;">int</span></strong> DFS<strong><span style="color:#ff00ff;">(</span><span style="color:blue;">int</span></strong> x<strong><span style="color:#ff00ff;">,</span><span style="color:blue;">int</span></strong> a<strong><span style="color:#ff00ff;">){</span><span style="color:#0000ff;">    if</span><span style="color:#ff00ff;">(</span></strong>x<strong><span style="color:#ff00ff;"> ==</span></strong> t<strong><span style="color:#ff00ff;"> ||</span></strong> a<strong><span style="color:#ff00ff;"> ==</span></strong><span style="color:#cc3300;"> 0</span><strong><span style="color:#ff00ff;">)</span><span style="color:#0000ff;"> return</span></strong> a<strong><span style="color:#ff00ff;">;</span><span style="color:blue;">    int</span></strong> flow<strong><span style="color:#ff00ff;"> =</span></strong><span style="color:#cc3300;"> 0</span><strong><span style="color:#ff00ff;"> ,</span></strong> f<strong><span style="color:#ff00ff;">;</span><span style="color:#0000ff;">    for</span><span style="color:#ff00ff;">(</span><span style="color:blue;">int</span><span style="color:#ff00ff;"> &</span></strong>i<strong><span style="color:#ff00ff;"> =</span></strong> cur<strong><span style="color:#ff00ff;">[</span></strong>x<strong><span style="color:#ff00ff;">];</span></strong>i<strong><span style="color:#ff00ff;"><</span></strong>G<strong><span style="color:#ff00ff;">[</span></strong>x<strong><span style="color:#ff00ff;">].</span></strong>size<strong><span style="color:#ff00ff;">();</span></strong>i<strong><span style="color:#ff00ff;">++)    {</span></strong>        Edge<strong><span style="color:#ff00ff;">&</span></strong> e<strong><span style="color:#ff00ff;"> =</span></strong> edges<strong><span style="color:#ff00ff;">[</span></strong>G<strong><span style="color:#ff00ff;">[</span></strong>x<strong><span style="color:#ff00ff;">][</span></strong>i<strong><span style="color:#ff00ff;">]];</span><span style="color:#0000ff;">        if</span><span style="color:#ff00ff;">(</span></strong>d<strong><span style="color:#ff00ff;">[</span></strong>x<strong><span style="color:#ff00ff;">] +</span></strong><span style="color:#cc3300;"> 1</span><strong><span style="color:#ff00ff;"> ==</span></strong> d<strong><span style="color:#ff00ff;">[</span></strong>e<strong><span style="color:#ff00ff;">.</span></strong>to<strong><span style="color:#ff00ff;">] && (</span></strong>f<strong><span style="color:#ff00ff;"> =</span></strong> DFS<strong><span style="color:#ff00ff;">(</span></strong>e<strong><span style="color:#ff00ff;">.</span></strong>to<strong><span style="color:#ff00ff;">,</span></strong>min<strong><span style="color:#ff00ff;">(</span></strong>a<strong><span style="color:#ff00ff;">,</span></strong>e<strong><span style="color:#ff00ff;">.</span></strong>cap<strong><span style="color:#ff00ff;">-</span></strong>e<strong><span style="color:#ff00ff;">.</span></strong>flow<strong><span style="color:#ff00ff;">))) ></span></strong><span style="color:#cc3300;"> 0</span><strong><span style="color:#ff00ff;">)        {</span></strong>            e<strong><span style="color:#ff00ff;">.</span></strong>flow<strong><span style="color:#ff00ff;"> +=</span></strong> f<strong><span style="color:#ff00ff;">;</span></strong>            edges<strong><span style="color:#ff00ff;">[</span></strong>G<strong><span style="color:#ff00ff;">[</span></strong>x<strong><span style="color:#ff00ff;">][</span></strong>i<strong><span style="color:#ff00ff;">]^</span></strong><span style="color:#cc3300;">1</span><strong><span style="color:#ff00ff;">].</span></strong>flow<strong><span style="color:#ff00ff;"> -=</span></strong> f<strong><span style="color:#ff00ff;">;</span></strong>            flow<strong><span style="color:#ff00ff;"> +=</span></strong> f<strong><span style="color:#ff00ff;">;</span></strong>            a<strong><span style="color:#ff00ff;"> -=</span></strong> f<strong><span style="color:#ff00ff;">;</span><span style="color:#0000ff;">            if</span><span style="color:#ff00ff;">(</span></strong>a<strong><span style="color:#ff00ff;"> ==</span></strong><span style="color:#cc3300;"> 0</span><strong><span style="color:#ff00ff;">)</span><span style="color:#0000ff;"> break</span><span style="color:#ff00ff;">;        }    }</span><span style="color:#0000ff;">    return</span></strong> flow<strong><span style="color:#ff00ff;">;}</span><span style="color:blue;">int</span></strong> Maxflow<strong><span style="color:#ff00ff;">(){</span><span style="color:blue;">    int</span></strong> flow<strong><span style="color:#ff00ff;"> =</span></strong><span style="color:#cc3300;"> 0</span><strong><span style="color:#ff00ff;">;</span><span style="color:#0000ff;">    while</span><span style="color:#ff00ff;">(</span></strong>BFS<strong><span style="color:#ff00ff;">())    {</span></strong>        memset<strong><span style="color:#ff00ff;">(</span></strong>cur<strong><span style="color:#ff00ff;">,</span></strong><span style="color:#cc3300;">0</span><strong><span style="color:#ff00ff;">,</span><span style="color:#0000ff;">sizeof</span><span style="color:#ff00ff;">(</span></strong>cur<strong><span style="color:#ff00ff;">));</span></strong>        flow<strong><span style="color:#ff00ff;"> +=</span></strong> DFS<strong><span style="color:#ff00ff;">(</span></strong>s<strong><span style="color:#ff00ff;">,</span></strong>INF<strong><span style="color:#ff00ff;">);    }</span><span style="color:#0000ff;">    return</span></strong> flow<strong><span style="color:#ff00ff;">;}</span><span style="color:blue;">int</span></strong> pre<strong><span style="color:#ff00ff;">[</span></strong>maxn<strong><span style="color:#ff00ff;">] ,</span></strong> lowlink<strong><span style="color:#ff00ff;">[</span></strong>maxn<strong><span style="color:#ff00ff;">] ,</span></strong>sccno<strong><span style="color:#ff00ff;">[</span></strong>maxn<strong><span style="color:#ff00ff;">] ,</span></strong> fa<strong><span style="color:#ff00ff;">[</span></strong>maxn<strong><span style="color:#ff00ff;">],</span></strong> dfs_clock<strong><span style="color:#ff00ff;"> ,</span></strong> scc_cnt<strong><span style="color:#ff00ff;"> ,</span></strong> flag<strong><span style="color:#ff00ff;">;</span></strong>stack<strong><span style="color:#ff00ff;"><</span><span style="color:blue;">int</span><span style="color:#ff00ff;">></span></strong> S<strong><span style="color:#ff00ff;">;</span><span style="color:blue;">void</span></strong> dfs<strong><span style="color:#ff00ff;">(</span><span style="color:blue;">int</span></strong> u<strong><span style="color:#ff00ff;">){</span></strong>    pre<strong><span style="color:#ff00ff;">[</span></strong>u<strong><span style="color:#ff00ff;">] =</span></strong> lowlink<strong><span style="color:#ff00ff;">[</span></strong>u<strong><span style="color:#ff00ff;">] = ++</span></strong>dfs_clock<strong><span style="color:#ff00ff;">;</span></strong>    S<strong><span style="color:#ff00ff;">.</span></strong>push<strong><span style="color:#ff00ff;">(</span></strong>u<strong><span style="color:#ff00ff;">);</span><span style="color:#0000ff;">    for</span><span style="color:#ff00ff;">(</span><span style="color:blue;">int</span></strong> i<strong><span style="color:#ff00ff;">=</span></strong><span style="color:#cc3300;">0</span><strong><span style="color:#ff00ff;">;</span></strong>i<strong><span style="color:#ff00ff;"><</span></strong>G<strong><span style="color:#ff00ff;">[</span></strong>u<strong><span style="color:#ff00ff;">].</span></strong>size<strong><span style="color:#ff00ff;">();</span></strong>i<strong><span style="color:#ff00ff;">++)    {</span></strong>        Edge<strong><span style="color:#ff00ff;">&</span></strong> e<strong><span style="color:#ff00ff;"> =</span></strong> edges<strong><span style="color:#ff00ff;">[</span></strong>G<strong><span style="color:#ff00ff;">[</span></strong>u<strong><span style="color:#ff00ff;">][</span></strong>i<strong><span style="color:#ff00ff;">]];</span><span style="color:#0000ff;">        if</span><span style="color:#ff00ff;">(</span></strong>e<strong><span style="color:#ff00ff;">.</span></strong>cap<strong><span style="color:#ff00ff;"> ==</span></strong> e<strong><span style="color:#ff00ff;">.</span></strong>flow<strong><span style="color:#ff00ff;">)</span><span style="color:#0000ff;"> continue</span><span style="color:#ff00ff;">;</span><span style="color:blue;">        int</span></strong> v<strong><span style="color:#ff00ff;"> =</span></strong> e<strong><span style="color:#ff00ff;">.</span></strong>to<strong><span style="color:#ff00ff;">;</span><span style="color:#0000ff;">        if</span><span style="color:#ff00ff;">(!</span></strong>pre<strong><span style="color:#ff00ff;">[</span></strong>v<strong><span style="color:#ff00ff;">])        {</span></strong>            fa<strong><span style="color:#ff00ff;">[</span></strong>v<strong><span style="color:#ff00ff;">] =</span></strong> u<strong><span style="color:#ff00ff;">;</span></strong>            dfs<strong><span style="color:#ff00ff;">(</span></strong>v<strong><span style="color:#ff00ff;">);</span><span style="color:#0000ff;">            if</span><span style="color:#ff00ff;">(!</span></strong>flag<strong><span style="color:#ff00ff;">)</span><span style="color:#0000ff;"> return</span><span style="color:#ff00ff;"> ;</span></strong>            lowlink<strong><span style="color:#ff00ff;">[</span></strong>u<strong><span style="color:#ff00ff;">] =</span></strong> min<strong><span style="color:#ff00ff;">(</span></strong>lowlink<strong><span style="color:#ff00ff;">[</span></strong>u<strong><span style="color:#ff00ff;">] ,</span></strong> lowlink<strong><span style="color:#ff00ff;">[</span></strong>v<strong><span style="color:#ff00ff;">]);        }</span><span style="color:#0000ff;">        else if</span><span style="color:#ff00ff;">(!</span></strong>sccno<strong><span style="color:#ff00ff;">[</span></strong>v<strong><span style="color:#ff00ff;">])        {</span></strong>         lowlink<strong><span style="color:#ff00ff;">[</span></strong>u<strong><span style="color:#ff00ff;">] =</span></strong> min<strong><span style="color:#ff00ff;">(</span></strong>lowlink<strong><span style="color:#ff00ff;">[</span></strong>u<strong><span style="color:#ff00ff;">] ,</span></strong> pre<strong><span style="color:#ff00ff;">[</span></strong>v<strong><span style="color:#ff00ff;">]);</span><span style="color:#0000ff;">         if</span><span style="color:#ff00ff;">(</span></strong>v<strong><span style="color:#ff00ff;"> !=</span></strong> fa<strong><span style="color:#ff00ff;">[</span></strong>u<strong><span style="color:#ff00ff;">]) {</span></strong>flag<strong><span style="color:#ff00ff;"> =</span></strong><span style="color:#cc3300;"> 0</span><strong><span style="color:#ff00ff;"> ;</span><span style="color:#0000ff;"> return</span><span style="color:#ff00ff;"> ;}        }    }</span><span style="color:#0000ff;">    if</span><span style="color:#ff00ff;">(</span></strong>lowlink<strong><span style="color:#ff00ff;">[</span></strong>u<strong><span style="color:#ff00ff;">] ==</span></strong> pre<strong><span style="color:#ff00ff;">[</span></strong>u<strong><span style="color:#ff00ff;">])    {</span></strong>        scc_cnt<strong><span style="color:#ff00ff;">++;</span><span style="color:#0000ff;">        for</span><span style="color:#ff00ff;">(;;)        {</span><span style="color:blue;">            int</span></strong> x<strong><span style="color:#ff00ff;"> =</span></strong> S<strong><span style="color:#ff00ff;">.</span></strong>top<strong><span style="color:#ff00ff;">();</span></strong> S<strong><span style="color:#ff00ff;">.</span></strong>pop<strong><span style="color:#ff00ff;">();</span></strong>            sccno<strong><span style="color:#ff00ff;">[</span></strong>x<strong><span style="color:#ff00ff;">] =</span></strong> scc_cnt<strong><span style="color:#ff00ff;">;</span><span style="color:#0000ff;">            if</span><span style="color:#ff00ff;">(</span></strong>x<strong><span style="color:#ff00ff;"> ==</span></strong> u<strong><span style="color:#ff00ff;">)</span><span style="color:#0000ff;"> break</span><span style="color:#ff00ff;">;        }    }}</span><span style="color:blue;">bool</span></strong> find_scc<strong><span style="color:#ff00ff;">(){</span></strong>    dfs_clock<strong><span style="color:#ff00ff;"> =</span></strong> scc_cnt<strong><span style="color:#ff00ff;"> =</span></strong><span style="color:#cc3300;"> 0</span><strong><span style="color:#ff00ff;">;</span></strong> flag<strong><span style="color:#ff00ff;"> =</span></strong><span style="color:#cc3300;"> 1</span><strong><span style="color:#ff00ff;">;</span></strong>    memset<strong><span style="color:#ff00ff;">(</span></strong>pre<strong><span style="color:#ff00ff;"> ,</span></strong><span style="color:#cc3300;"> 0</span><strong><span style="color:#ff00ff;">,</span><span style="color:#0000ff;"> sizeof</span><span style="color:#ff00ff;">(</span></strong>pre<strong><span style="color:#ff00ff;">));</span></strong>    memset<strong><span style="color:#ff00ff;">(</span></strong>lowlink<strong><span style="color:#ff00ff;"> ,</span></strong><span style="color:#cc3300;"> 0</span><strong><span style="color:#ff00ff;">,</span><span style="color:#0000ff;"> sizeof</span><span style="color:#ff00ff;">(</span></strong>lowlink<strong><span style="color:#ff00ff;">));</span></strong>    memset<strong><span style="color:#ff00ff;">(</span></strong>sccno<strong><span style="color:#ff00ff;"> ,</span></strong><span style="color:#cc3300;"> 0</span><strong><span style="color:#ff00ff;"> ,</span><span style="color:#0000ff;"> sizeof</span><span style="color:#ff00ff;">(</span></strong>sccno<strong><span style="color:#ff00ff;">));</span><span style="color:#0000ff;">    for</span><span style="color:#ff00ff;">(</span><span style="color:blue;">int</span></strong> i<strong><span style="color:#ff00ff;">=</span></strong><span style="color:#cc3300;">0</span><strong><span style="color:#ff00ff;">;</span></strong>i<strong><span style="color:#ff00ff;"><</span></strong>n<strong><span style="color:#ff00ff;">;</span></strong>i<strong><span style="color:#ff00ff;">++)</span><span style="color:#0000ff;">    if</span><span style="color:#ff00ff;">(!</span></strong>pre<strong><span style="color:#ff00ff;">[</span></strong>i<strong><span style="color:#ff00ff;">]) {</span></strong> dfs<strong><span style="color:#ff00ff;">(</span></strong>i<strong><span style="color:#ff00ff;">);</span><span style="color:#0000ff;"> if</span><span style="color:#ff00ff;">(!</span></strong>flag<strong><span style="color:#ff00ff;">)</span><span style="color:#0000ff;"> return</span></strong><span style="color:#cc3300;"> 0</span><strong><span style="color:#ff00ff;">;}</span><span style="color:#0000ff;">    return</span></strong><span style="color:#cc3300;"> 1</span><strong><span style="color:#ff00ff;">;}</span><span style="color:blue;">int</span><span style="color:#0000ff;"> main</span><span style="color:#ff00ff;">(){</span><span style="color:blue;">    int</span></strong> T<strong><span style="color:#ff00ff;"> ,</span></strong> kcase<strong><span style="color:#ff00ff;"> =</span></strong><span style="color:#cc3300;"> 1</span><strong><span style="color:#ff00ff;">;</span><span style="color:blue;">    int</span></strong> N<strong><span style="color:#ff00ff;"> ,</span></strong> M<strong><span style="color:#ff00ff;"> ,</span></strong> K<strong><span style="color:#ff00ff;">;</span></strong>    scanf<strong><span style="color:#ff00ff;">(</span></strong><span style="color:green;">"%d"</span><strong><span style="color:#ff00ff;">,&</span></strong>T<strong><span style="color:#ff00ff;">);</span><span style="color:#0000ff;">    while</span><span style="color:#ff00ff;">(</span></strong>T<strong><span style="color:#ff00ff;">--)    {</span></strong>        scanf<strong><span style="color:#ff00ff;">(</span></strong><span style="color:green;">"%d%d"</span><strong><span style="color:#ff00ff;">,&</span></strong>N<strong><span style="color:#ff00ff;">,&</span></strong>M<strong><span style="color:#ff00ff;">);</span></strong>        K<strong><span style="color:#ff00ff;"> =</span></strong><span style="color:#cc3300;"> 9</span><strong><span style="color:#ff00ff;">;</span></strong>s<strong><span style="color:#ff00ff;"> =</span></strong><span style="color:#cc3300;"> 0</span><strong><span style="color:#ff00ff;"> ,</span></strong> t<strong><span style="color:#ff00ff;"> =</span></strong> N<strong><span style="color:#ff00ff;"> +</span></strong> M<strong><span style="color:#ff00ff;"> +</span></strong><span style="color:#cc3300;"> 1</span><strong><span style="color:#ff00ff;">;</span></strong>        n<strong><span style="color:#ff00ff;"> =</span></strong> t<strong><span style="color:#ff00ff;"> +</span></strong><span style="color:#cc3300;"> 1</span><strong><span style="color:#ff00ff;">;</span></strong> init<strong><span style="color:#ff00ff;">();</span><span style="color:blue;">        int</span></strong> sumr<strong><span style="color:#ff00ff;"> =</span></strong><span style="color:#cc3300;"> 0</span><strong><span style="color:#ff00ff;"> ,</span></strong> sumc<strong><span style="color:#ff00ff;"> =</span></strong><span style="color:#cc3300;"> 0</span><strong><span style="color:#ff00ff;">;</span><span style="color:blue;">        int</span></strong> x<strong><span style="color:#ff00ff;">;</span><span style="color:#0000ff;">        for</span><span style="color:#ff00ff;">(</span><span style="color:blue;">int</span></strong> i<strong><span style="color:#ff00ff;">=</span></strong><span style="color:#cc3300;">1</span><strong><span style="color:#ff00ff;">;</span></strong>i<strong><span style="color:#ff00ff;"><=</span></strong>N<strong><span style="color:#ff00ff;">;</span></strong>i<strong><span style="color:#ff00ff;">++)        {</span></strong>            scanf<strong><span style="color:#ff00ff;">(</span></strong><span style="color:green;">"%d"</span><strong><span style="color:#ff00ff;">,&</span></strong>x<strong><span style="color:#ff00ff;">);</span></strong>            AddEdge<strong><span style="color:#ff00ff;">(</span></strong>s<strong><span style="color:#ff00ff;"> ,</span></strong> i<strong><span style="color:#ff00ff;"> ,</span></strong> x<strong><span style="color:#ff00ff;">);</span></strong>            sumr<strong><span style="color:#ff00ff;"> +=</span></strong> x<strong><span style="color:#ff00ff;">;        }</span><span style="color:#0000ff;">        for</span><span style="color:#ff00ff;">(</span><span style="color:blue;">int</span></strong> i<strong><span style="color:#ff00ff;">=</span></strong><span style="color:#cc3300;">1</span><strong><span style="color:#ff00ff;">;</span></strong>i<strong><span style="color:#ff00ff;"><=</span></strong>M<strong><span style="color:#ff00ff;">;</span></strong>i<strong><span style="color:#ff00ff;">++)        {</span></strong>            scanf<strong><span style="color:#ff00ff;">(</span></strong><span style="color:green;">"%d"</span><strong><span style="color:#ff00ff;">,&</span></strong>x<strong><span style="color:#ff00ff;">);</span></strong>            AddEdge<strong><span style="color:#ff00ff;">(</span></strong>i<strong><span style="color:#ff00ff;"> +</span></strong> N<strong><span style="color:#ff00ff;"> ,</span></strong> t<strong><span style="color:#ff00ff;"> ,</span></strong> x<strong><span style="color:#ff00ff;">);</span></strong>            sumc<strong><span style="color:#ff00ff;"> +=</span></strong> x<strong><span style="color:#ff00ff;">;        }</span></strong>        printf<strong><span style="color:#ff00ff;">(</span></strong><span style="color:green;">"Case #%d: "</span><strong><span style="color:#ff00ff;">,</span></strong>kcase<strong><span style="color:#ff00ff;">++);</span><span style="color:#0000ff;">        if</span><span style="color:#ff00ff;"> (</span></strong>sumr<strong><span style="color:#ff00ff;"> !=</span></strong> sumc<strong><span style="color:#ff00ff;">){</span></strong> printf<strong><span style="color:#ff00ff;">(</span></strong><span style="color:green;">"So naive!\n"</span><strong><span style="color:#ff00ff;">);</span><span style="color:#0000ff;">continue</span><span style="color:#ff00ff;">; }</span><span style="color:#0000ff;">        for</span><span style="color:#ff00ff;">(</span><span style="color:blue;">int</span></strong> i<strong><span style="color:#ff00ff;">=</span></strong><span style="color:#cc3300;">1</span><strong><span style="color:#ff00ff;">;</span></strong>i<strong><span style="color:#ff00ff;"><=</span></strong>N<strong><span style="color:#ff00ff;">;</span></strong>i<strong><span style="color:#ff00ff;">++)        {</span><span style="color:#0000ff;">            for</span><span style="color:#ff00ff;">(</span><span style="color:blue;">int</span></strong> j<strong><span style="color:#ff00ff;">=</span></strong><span style="color:#cc3300;">1</span><strong><span style="color:#ff00ff;">;</span></strong>j<strong><span style="color:#ff00ff;"><=</span></strong>M<strong><span style="color:#ff00ff;">;</span></strong>j<strong><span style="color:#ff00ff;">++)            {</span></strong>                AddEdge<strong><span style="color:#ff00ff;">(</span></strong>i<strong><span style="color:#ff00ff;"> ,</span></strong> j<strong><span style="color:#ff00ff;"> +</span></strong> N<strong><span style="color:#ff00ff;"> ,</span></strong> K<strong><span style="color:#ff00ff;">);            }        }</span><span style="color:blue;">        int</span></strong> ans<strong><span style="color:#ff00ff;"> =</span></strong> Maxflow<strong><span style="color:#ff00ff;">();</span><span style="color:#0000ff;">        if</span><span style="color:#ff00ff;">(</span></strong>ans<strong><span style="color:#ff00ff;"> !=</span></strong> sumr<strong><span style="color:#ff00ff;">) {</span></strong> printf<strong><span style="color:#ff00ff;">(</span></strong><span style="color:green;">"So naive!\n"</span><strong><span style="color:#ff00ff;">);</span><span style="color:#0000ff;"> continue</span><span style="color:#ff00ff;">; }</span><span style="color:#0000ff;">        if</span><span style="color:#ff00ff;">(</span></strong>find_scc<strong><span style="color:#ff00ff;">())</span></strong> printf<strong><span style="color:#ff00ff;">(</span></strong><span style="color:green;">"So simple!\n"</span><strong><span style="color:#ff00ff;">);</span><span style="color:#0000ff;">        else</span></strong> printf<strong><span style="color:#ff00ff;">(</span></strong><span style="color:green;">"So young!\n"</span><strong><span style="color:#ff00ff;">);    }</span><span style="color:#0000ff;">    return</span></strong><span style="color:#cc3300;"> 0</span><strong><span style="color:#ff00ff;">;}</span></strong>