hdu 1532 Drainage Ditches（EK算法）

输入m n,   m是边数，n是点数。

接下来m行:   起点，终点，最大流量。

#include <cstdio>
#include <iostream>
#include <cstring>
#include <string>
#include <cstdlib>
#include <algorithm>
#include <cmath>
#include <vector>
#include <set>
#include <list>
#include <queue>
#include <map>
using namespace std;
#define INF 0x3f3f3f3f

int flow[220][220];
int vis[220],pre[220];
int n,m;

int max_flow()
{
int ans = 0;
while(1)
{
memset(vis,0,sizeof(vis));
memset(pre,0,sizeof(pre));
queue<int> Q;
vis[1] = 1;
Q.push(1);
while(!Q.empty())
{
int cnt = Q.front();
Q.pop();
if(cnt == n)
break;
for(int i = 1; i <= n; i++)
if(!vis[i] && flow[cnt][i] > 0)
{
vis[i] = 1;
pre[i] = cnt;
Q.push(i);
}
}
if(!vis
)
break;
int Max = INF;
for(int i = n; i != 1; i = pre[i])
Max = min(Max,flow[pre[i]][i]);
for(int i = n; i != 1; i = pre[i])
{
flow[pre[i]][i] -= Max;
flow[i][pre[i]] += Max;
}
ans += Max;
}
return ans;
}
int main()
{
int t,C = 1;
//scanf("%d",&t);
while(scanf("%d%d",&m,&n) != EOF)
{
memset(flow,0,sizeof(flow));
for(int i = 0; i < m; i++)
{
int u,v,w;
scanf("%d%d%d",&u,&v,&w);
flow[u][v] += w;
}
printf("%d\n",max_flow());
}
}