tjut 3061

来源：互联网发布：紫外线杀菌灯知乎编辑：程序博客网时间：2024/06/05 19:54
#include <stdio.h>  #include <string.h>  #define VM 10000  #define EM 120000  #define inf 0x3f3f3f3f  struct E  {      int to,cap,nxt;  }edge[EM];    int head[VM],gap[VM],dist[VM],cur[VM],pre[VM];  int ep;  void addedge (int cu,int cv,int cw)  {        edge[ep].to = cv;      edge[ep].cap = cw;      edge[ep].nxt = head[cu];      head[cu] = ep;      ep ++;      edge[ep].to = cu;      edge[ep].cap = 0;      edge[ep].nxt = head[cv];      head[cv] = ep;      ep ++;  }  int min (int a ,int b)  {     return a > b ? b : a;  }    int sap (int src,int des,int n)  {        memset (dist,0,sizeof(dist));      memset (gap,0,sizeof (dist));      memcpy (cur,head,sizeof(dist));      int res = 0;      int u = pre[src] = src;      int aug = inf;      gap[0] = n;      while (dist[src] < n)      {  loop:          for (int &i = cur[u];i != -1;i = edge[i].nxt)          {              int v = edge[i].to;              if (edge[i].cap && dist[u] == dist[v] + 1)              {                  aug = min (aug,edge[i].cap);                  pre[v] = u;                  u = v;                  if (v == des)                  {                      res += aug;                      for (u = pre[u];v != src;v = u,u = pre[u])                      {                          edge[cur[u]].cap -= aug;                          edge[cur[u]^1].cap += aug;                      }                      aug = inf; //                  }                  goto loop;              }          }          int mindist = n;  //          for (int i = head[u];i != -1;i = edge[i].nxt)          {              int v = edge[i].to;              if (edge[i].cap && mindist > dist[v])              {                  cur[u] = i;                  mindist = dist[v];              }          }          if ((--gap[dist[u]]) == 0)              break;          dist[u] = mindist + 1;          gap[dist[u]] ++;          u = pre[u];      }      return res;  }  int vis[VM];  void dfs(int u,int v)  {      if(u==v) return ;      vis[u]=1;      for(int i=head[u];i!=-1;i=edge[i].nxt)      if(edge[i].cap>0&&!vis[edge[i].to])      dfs(edge[i].to,v);  }  int main ()  {      int n,m,u,v,p;      int src,des;      int sum;      while (scanf("%d %d",&n,&m)!=EOF)      {          ep = 0;          sum=0;          src = 0;          des = n + 1;          memset (head,-1,sizeof(head));          for(int i=1;i<=n;i++)          {              scanf("%d",&p);              if(p>0)              {                  addedge(src,i,p);                  sum+=p;              }              else              addedge(i,des,-p);          }          for (int i=1; i<=m; i++)          {              scanf("%d%d",&u,&v);              addedge(u,v,inf);          }          int max_flow=sap(src,des,n + 2);;            printf("%d\n",sum-max_flow);      }      return 0;  }
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