HDU 1532 Drainage Ditches 最大流 （Edmonds_Karp）

题目链接： http://acm.hdu.edu.cn/showproblem.php?pid=1532

感觉题意不清楚，不知道是不是个人英语水平问题。本来还以为需要维护入度和出度来找源点和汇点呢，看讨论才知道1就是起点，m就是汇点。。好想把代码写的工程化一点。

 #include <stdio.h>
 #include <string.h>
 #include <queue>
 #include <algorithm>
 using namespace std;

 const int INF = 0x3f3f3f3f;
 int n, m;
 int cap[][], flow[][], res[], pre[];
 queue<int>que;

 int Edmonds_Karp()
 {
     while(!que.empty())
     {
         que.pop();
     }
     int flow_sum = ;
     while(true)
     {
         memset(res, , sizeof(res));
         res[] = INF;
         que.push();
         while(!que.empty())
         {
             int u = que.front();
             que.pop();
             for(int v = ; v <= m; v++)
             {
                 if(!res[v] && cap[u][v] > flow[u][v])
                 {
                     pre[v] = u;
                     que.push(v);
                     res[v] = min(res[u], cap[u][v] - flow[u][v]);
                 }
             }
         }
         if(res[m] == )break;
         for(int u = m; u != ; u = pre[u])
         {
             flow[pre[u]][u] += res[m];
             flow[u][pre[u]] -= res[m];
         }
         flow_sum += res[m];
     }
     return flow_sum;
 }

 int main()
 {
     int u, v, w;
     while(scanf("%d %d", &n, &m) != EOF)
     {
         memset(cap, , sizeof(cap));
         memset(flow, , sizeof(flow));
         for(int i = ; i < n; i++)
         {
             scanf("%d %d %d", &u, &v, &w);
             cap[u][v] += w;
         }
         printf("%d\n", Edmonds_Karp());
     }
     return ;
 }