POJ-3469 Dual Core CPU 网络流

http://poj.org/problem?id=3469

题意：一台双核电脑，给你多个任务，分别给出每个任务在第一个核和第二个核上运行的消耗。后面的m行输入是给出两个任务在两个不同核上运行需要付出的额外消耗。

建图：把每个任务作为节点，在超级源点与任务间的连一条边，其容量为给任务在核1上运行的消耗，在该任务节点与超级汇点之间连一条边，容量为该任务在核2上运行的消耗。

           在任务之间连接无向边，容量为两个任务不在同一核上运行的额外消耗。

搞了一天，ISPA 2S无压力 dinic看了各种版本的题解就只能到4S 不理解了 可能自己还有什么地方没考虑到吧

3469Accepted6184K2219MSC++2192B

#include "stdio.h"#include "queue"#include "string.h"#include "algorithm"using namespace std;const int maxn = 20020;const int inf = 1<<30;int n,pos;int head[maxn];struct node{int v,w,next;node(){}node( int v,int w,int next ):v(v),w(w),next(next){}}edge[30*maxn];void add( int u,int v,int w,int ww ){edge[pos].v = v; edge[pos].w = w; edge[pos].next = head[u];head[u] = pos++;edge[pos].v = u; edge[pos].w = ww; edge[pos].next = head[v];head[v] = pos++;}int SAP_Max_Flow( int st,int end ){int cur[maxn],pre[maxn],h[maxn],gap[maxn];int u,neck,tmp,i;memset( h,0,sizeof(h) );memset( gap,0,sizeof(gap) );int cur_flow,flow_ans = 0;for( int i = 0; i <= n; i ++ )cur[i] = head[i];gap[0] = n+1;u = st;while( h[st] < n+1 ){if( u == end ){cur_flow = inf;for( i = st; i != end; i = edge[cur[i]].v ){if( cur_flow > edge[cur[i]].w ){neck = i;cur_flow = edge[cur[i]].w;}}for( i = st; i != end; i = edge[cur[i]].v ){tmp = cur[i];edge[tmp].w -= cur_flow;edge[tmp^1].w += cur_flow;}flow_ans += cur_flow;u = neck;}for( i = cur[u]; i != -1; i = edge[i].next ){if( edge[i].w && h[u] == h[edge[i].v] + 1 )break;}if( i != -1 ){cur[u] = i;pre[edge[i].v] = u;u = edge[i].v;}else{if( 0 == --gap[h[u]] )break;cur[u] = head[u];for( tmp = n,i = head[u]; i != -1; i = edge[i].next )if( edge[i].w )tmp = tmp < h[edge[i].v]?tmp:h[edge[i].v];h[u] = tmp + 1;gap[h[u]] ++;if( u != st )u = pre[u];}}return flow_ans;}int main(){    //freopen("data.txt","r",stdin);int nt,m,a,b,c;    while( scanf("%d%d",&nt,&m) == 2 ){pos = 0;n = nt + 1;for( int i = 0; i <= n; i ++ )head[i] = -1;for( int i = 1; i <= nt; i ++ ){scanf("%d%d",&a,&b);add(0,i,a,0);add(i,n,b,0);}for( int i = 1; i <= m; i ++ ){scanf("%d%d%d",&a,&b,&c);add(a,b,c,c);}printf("%d\n",SAP_Max_Flow(0,n));}    return 0;}

3469Accepted6188K4438MSC++2014B

#include "stdio.h"#include "queue"#include "string.h"#include "algorithm"using namespace std;const int maxn = 20020;const int inf = 1<<30;int n,pos;int head[maxn],dis[maxn];struct node{int v,w,next;node(){}node( int v,int w,int next ):v(v),w(w),next(next){}}edge[30*maxn];void add( int u,int v,int w,int ww ){edge[pos].v = v; edge[pos].w = w; edge[pos].next = head[u];head[u] = pos++;edge[pos].v = u; edge[pos].w = ww; edge[pos].next = head[v];head[v] = pos++;}int mins( int a,int b ){return a < b?a:b;}bool Dinic_bfs( int st ){queue<int>que;for( int i = 0; i <= n; i ++ )dis[i] = -1;dis[st] = 0;que.push(st);while( !que.empty() ){int u = que.front();  que.pop();for( int i = head[u]; i != -1; i = edge[i].next  ){node v = edge[i];if( v.w && dis[v.v] == -1 ){dis[v.v] = dis[u] + 1;que.push(v.v);if( v.v == n )return true;}}}return false;}int Dinic_dfs( int u,int maxf ){if( u == n )return maxf;int ans = 0, flow;for( int i = head[u]; i != -1 && ans < maxf; i = edge[i].next ){if( edge[i].w && dis[edge[i].v] == dis[u] + 1 ){if( flow =  Dinic_dfs( edge[i].v,mins(edge[i].w,maxf-ans) )){  edge[i].w -= flow;edge[i^1].w += flow;ans += flow;}}}if( !ans )//关键的一句话dis[u] = -1;return ans;}int Dinic( int st,int end ){int ans = 0,flow;while( Dinic_bfs(st) ){while( flow = Dinic_dfs( st,inf ) )  //增广  ans += flow;}return ans;}int main(){    //freopen("data.txt","r",stdin);int nt,m,a,b,c;    while( scanf("%d%d",&nt,&m) == 2 ){int s = 0;pos = 0;n = nt + 1;for( int i = 0; i <= n; i ++ )head[i] = -1;for( int i = 1; i <= nt; i ++ ){scanf("%d%d",&a,&b);add(0,i,a,0);add(i,n,b,0);}for( int i = 1; i <= m; i ++ ){scanf("%d%d%d",&a,&b,&c);add(a,b,c,c);}printf("%d\n",Dinic(s,n));}    return 0;}

3469Accepted6256K4204MSC++2005B

#include "stdio.h"#include "queue"#include "string.h"#include "algorithm"using namespace std;const int maxn = 20020;const int inf = 1<<30;int n,pos;int head[maxn],cur[maxn],dis[maxn];struct node{int v,w,next;node(){}node( int v,int w,int next ):v(v),w(w),next(next){}}edge[30*maxn];void add( int u,int v,int w,int ww ){edge[pos].v = v; edge[pos].w = w; edge[pos].next = head[u];head[u] = pos++;edge[pos].v = u; edge[pos].w = ww; edge[pos].next = head[v];head[v] = pos++;}int mins( int a,int b ){return a < b?a:b;}bool Dinic_bfs( int st ){queue<int>que;for( int i = 0; i <= n; i ++ )dis[i] = -1;dis[st] = 0;que.push(st);while( !que.empty() ){int u = que.front();  que.pop();for( int i = head[u]; i != -1; i = edge[i].next  ){node v = edge[i];if( v.w && dis[v.v] == -1 ){dis[v.v] = dis[u] + 1;que.push(v.v);if( v.v == n )return true;}}}return false;}int Dinic_dfs( int u,int maxf ){if( u == n )return maxf;int ans = 0, flow;for( int &i = cur[u]; i != -1 && ans < maxf; i = edge[i].next ){if( edge[i].w && dis[edge[i].v] == dis[u] + 1 ){if( flow =  Dinic_dfs( edge[i].v,mins(edge[i].w,maxf-ans) )){  edge[i].w -= flow;edge[i^1].w += flow;return flow;}}}return 0;}int Dinic( int st,int end ){int ans = 0,flow;while( Dinic_bfs(st) ){memcpy(cur,head,sizeof(head));while( flow = Dinic_dfs( st,inf ) )  //增广  ans += flow;}return ans;}int main(){    //freopen("data.txt","r",stdin);int nt,m,a,b,c;    while( scanf("%d%d",&nt,&m) == 2 ){pos = 0;n = nt + 1;for( int i = 0; i <= n; i ++ )head[i] = -1;for( int i = 1; i <= nt; i ++ ){scanf("%d%d",&a,&b);add(0,i,a,0);add(i,n,b,0);}for( int i = 1; i <= m; i ++ ){scanf("%d%d%d",&a,&b,&c);add(a,b,c,c);}printf("%d\n",Dinic(0,n));}    return 0;}

3469Accepted6112K2844MSC++2376B

#include <iostream>using namespace std;const int nMax = 20030;const int mMax = 230000;const int inf = 0x7fffffff;int head[nMax], temp[nMax];int que[nMax], level[nMax];int ne;struct Edge{int v, c, next;} edges[2*(nMax+mMax)];void addEdges(int from, int to, int val1, int val2){   edges[ne].v = to;   edges[ne].c = val1;   edges[ne].next = head[from];   head[from] = ne++;   edges[ne].v = from;   edges[ne].c = val2;   edges[ne].next = head[to];   head[to] = ne++;}int Dinic(int sta, int end){int max = 0;    int i, k, curr;    while(true){memset(level, -1, sizeof(level));    int f, r;        f = 0; r = 1;que[0] = sta;level[sta] = 0;        while(f < r){curr = que[f++];for(i = head[curr]; i; i = edges[i].next)if(edges[i].c && level[k = edges[i].v] == -1){level[k] = level[curr] + 1;que[r++] = k;if(k == end){ f = r; break; }}}if(level[end] == -1) break;        memcpy(temp, head, sizeof(temp));int top;for(curr = sta, top = 0; ;){if(curr == end){  int tp = inf;   for(i = 0; i < top; i++)                    if(tp > edges[que[i]].c)tp = edges[que[f = i]].c;for(i = 0; i < top; i++){edges[que[i]].c -= tp;edges[que[i]^1].c += tp;}top = f;                max += tp; curr = edges[que[top-1]].v;}for(i = temp[curr]; temp[curr]; i = temp[curr] = edges[temp[curr]].next)if(edges[i].c && level[edges[i].v] == level[curr] + 1)break;            if(temp[curr]){que[top++] = temp[curr];    curr = edges[temp[curr]].v;}else{if(top == 0) break;level[curr] = -1;if((top--) == 1)curr = sta;else    curr = edges[head[top-1]].v;}}}return max;}int main(){int n, m;    int k, j, val1, val2;    int i;    //freopen("a.txt", "r", stdin);ne = 2;memset(head, 0, sizeof(head));scanf("%d%d", &n, &m);for(i = 1; i <= n; i++){       scanf("%d%d", &val1, &val2);   addEdges(0, i, val1, 0);   addEdges(i, n+1, val2, 0);}for(i = 1; i <= m; i++){scanf("%d%d%d", &k, &j, &val1);        addEdges(k, j, val1, val1);}printf("%d\n", Dinic(0, n+1));return 0;}

3469Accepted6148K3469MSC++2045B

#include<cstdio>  using namespace std;  const int mm=1000000;  const int mn=22222;  const int oo=1000000000;  int node,src,dest,edge;  int reach[mm],flow[mm],next[mm];  int head[mn],work[mn],dis[mn],q[mn];  inline int min(int a,int b)  {      return a<b?a:b;  }  inline void prepare(int _node,int _src,int _dest)  {      node=_node,src=_src,dest=_dest;      for(int i=0;i<node;++i)head[i]=-1;      edge=0;  }  inline void addedge(int u,int v,int c1,int c2)  {      reach[edge]=v,flow[edge]=c1,next[edge]=head[u],head[u]=edge++;      reach[edge]=u,flow[edge]=c2,next[edge]=head[v],head[v]=edge++;  }  bool Dinic_bfs()  {      int i,u,v,l,r=0;      for(i=0;i<node;++i)dis[i]=-1;      dis[q[r++]=src]=0;      for(l=0;l<r;++l)          for(i=head[u=q[l]];i>=0;i=next[i])              if(flow[i]&&dis[v=reach[i]]<0)              {                  dis[q[r++]=v]=dis[u]+1;                  if(v==dest)return 1;              }      return 0;  }  int Dinic_dfs(int u,int exp)  {      if(u==dest)return exp;      for(int &i=work[u],v,tmp;i>=0;i=next[i])          if(flow[i]&&dis[v=reach[i]]==dis[u]+1&&(tmp=Dinic_dfs(v,min(exp,flow[i])))>0)          {              flow[i]-=tmp;              flow[i^1]+=tmp;              return tmp;          }      return 0;  }  int Dinic_flow()  {      int i,ret=0,delta;      while(Dinic_bfs())      {          for(i=0;i<node;++i)work[i]=head[i];          while(delta=Dinic_dfs(src,oo))ret+=delta;      }      return ret;  }  int main()  {      int i,j,n,m,a,b;      while(scanf("%d%d",&n,&m)!=-1)      {          prepare(n+2,0,n+1);          for(i=1;i<=n;++i)          {              scanf("%d%d",&a,&b);              addedge(src,i,a,0);              addedge(i,dest,b,0);          }          while(m--)          {              scanf("%d%d%d",&i,&j,&a);              addedge(i,j,a,a);          }          printf("%d\n",Dinic_flow());      }      return 0;  }