hdu1532 （最大流入门，EK算法）

看着这个博客

然后敲了hdu1532这个入门题，算是对最大流有点理解了

 #include <stdio.h>
 #include <string.h>
 #include <queue>
 using namespace std;
 const int INF = <<;
 const int N =  + ;
 int n,m;
 int cap[N][N],flow[N],pre[N];
 int bfs(int src, int des)//每次用bfs找到最小的delta
 {
     queue<int> q;
     for(int i=;i<=n; ++i)
         pre[i] = -;
     pre[src] = ;
     flow[src] = INF;
     q.push(src);
     while(!q.empty())
     {
         int u = q.front(); q.pop();

         for(int i=;i<=n;++i)
         if(i!=src && cap[u][i]> && pre[i]==-)
         {
             pre[i] = u;
             flow[i] = min(cap[u][i],flow[u]);
             q.push(i);
         }
     }
     //printf("%d\n",pre[des]);
     if(pre[des]==-)
         return -;
     else
         return flow[des];
 }
 int maxFlow(int src, int des)
 {
     int sumFlow = ;
     int add = ;
     while((add = bfs(src,des)) != -)//如果不为-1，那么就进行增广
     {
         int k = des;
         while(k!=src)
         {
             int fa = pre[k];
             cap[fa][k] -= add;
             cap[k][fa] += add;
             k = fa;
         }
         sumFlow += add;
     }
     return sumFlow;

 }
 int main()
 {

     while(scanf("%d%d",&m,&n)!=EOF)
     {
         int u,v,c;
         memset(cap,,sizeof(cap));
         for(int i=;i<=m;++i)
         {
             scanf("%d%d%d",&u,&v,&c);
             cap[u][v] += c;

         }
         int ans = maxFlow(,n);
         printf("%d\n",ans);
     }
     return ;
 }