hdu 3338 Kakuro Extension(最大流)

来源：互联网发布：grpc java 使用编辑：程序博客网时间：2024/06/12 19:13

这题写的好忧桑~由于不愿意读题，所以看样例yy了一下，结果写完发现每个格要填1~9，然后无语地写了个上下界的网络流，写完交上去TLE了Orz……

由于每个格子至少都要填1，那么不妨一开始就在总量中把这个1减去，每一行(列)的容量修改为它减去它右(下)面空格的数量。这样就相当于在原来的图中填入0~8，这样问题就简单了。

代码：

#include<iostream>#include<cstdio>#include<cstring>#include<string>#include<algorithm>#include<map>#include<queue>#include<stack>#include<cmath>#include<vector>#define inf 0x3f3f3f3f#define Inf 0x3FFFFFFFFFFFFFFFLL#define eps 1e-9#define pi acos(-1.0)using namespace std;typedef long long ll;const int maxn=20000+10;const int maxm=200000+10;struct Edge{    int to,cap,flow,next;    Edge(){}    Edge(int to,int cap,int flow,int next):to(to),cap(cap),flow(flow),next(next){}}edges[maxm<<1];int head[maxn],d[maxn],cur[maxn],nEdge;void AddEdges(int from,int to,int cap){    edges[++nEdge]=Edge(to,cap,0,head[from]);    head[from]=nEdge;    edges[++nEdge]=Edge(from,0,0,head[to]);    head[to]=nEdge;}bool BFS(int s,int t){    memset(d,0xff,sizeof(d));    queue<int>q;    q.push(s);    d[s]=0;    while(!q.empty())    {        int u=q.front();q.pop();        for(int k=head[u];k!=-1;k=edges[k].next)        {            Edge e=edges[k];            if(d[e.to]==-1&&e.cap>e.flow)            {                d[e.to]=d[u]+1;                q.push(e.to);            }        }    }    return d[t]!=-1;}int DFS(int u,int a,int t){    if(u==t||a==0) return a;    int flow=0,f;    for(int &k=cur[u];k!=-1;k=edges[k].next)    {        Edge e=edges[k];        if(d[e.to]==d[u]+1&&(f=DFS(e.to,min(a,e.cap-e.flow),t))>0)        {            edges[k].flow+=f;            edges[k^1].flow-=f;            a-=f;flow+=f;            if(a==0) break;        }    }    return flow;}int MaxFlow(int s,int t){    int flow=0;    while(BFS(s,t))    {        for(int i=0;i<=t;++i) cur[i]=head[i];        flow+=DFS(s,inf,t);    }    return flow;}struct Node{    int id,type,vx,vy;    Node(){};    Node(int id,int type,int vx,int vy):id(id),type(type),vx(vx),vy(vy){}}node[111][111];char str[11];int indx[111][111];Node NewNode(const char *str,int id){    if(str[3]=='.') return Node(id,0,-1,-1);    if(str[3]=='X') return Node(id,2,-1,-1);    int x=-1,y=-1;    if(str[4]!='X') x=(str[6]-'0')+(str[5]-'0')*10+(str[4]-'0')*100;    if(str[0]!='X') y=(str[2]-'0')+(str[1]-'0')*10+(str[0]-'0')*100;    return Node(id,1,x,y);}int main(){    //freopen("in.txt","r",stdin);    //freopen("out.txt","w",stdout);    int n,m;    while(~scanf("%d%d",&n,&m))    {        memset(head,0xff,sizeof(head));        nEdge=-1;        for(int i=0;i<n;++i)            for(int j=0;j<m;++j)            {                scanf("%s",str);                node[i][j]=NewNode(str,i*m+j+1);            }        int S=0,T=n*m+n*m+1;        for(int i=0;i<n;++i)        {            int j=0;            for(;j<m;++j)            {                if(node[i][j].type==1&&node[i][j].vx!=-1)                {                    int k=0;                    while(k+j+1<m&&node[i][k+j+1].type==0) k++;                    AddEdges(S,node[i][j].id,node[i][j].vx-k);                    for(int l=1;l<=k;++l)                        AddEdges(node[i][j].id,node[i][j+l].id,8);                    j+=k;                }            }        }        for(int j=0;j<m;++j)        {            int i=0;            for(;i<n;++i)            {                if(node[i][j].type==1&&node[i][j].vy!=-1)                {                    int k=0;                    while(k+i+1<n&&node[i+k+1][j].type==0) k++;                    AddEdges(node[i][j].id+n*m,T,node[i][j].vy-k);                    for(int l=1;l<=k;++l)                    {                        AddEdges(node[i+l][j].id,node[i][j].id+n*m,8);                        indx[i+l][j]=nEdge-1;                    }                    i+=k;                }            }        }        MaxFlow(S,T);        for(int i=0;i<n;++i)        {            for(int j=0;j<m;++j)            {                if(j) printf(" ");                if(node[i][j].type) printf("_");                else printf("%d",edges[indx[i][j]].flow+1);            }            printf("\n");        }    }    return 0;}

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