【HDU】 1532 Drainage Ditches

Drainage Ditches

题目链接

题目大意

题解

代码

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>

using namespace std;

int u,v,dist,a[205][205],flow[205],pre[205],q[205],n,m;

int bfs(int s,int des)
{
memset(q,0,sizeof(q));
memset(pre,0,sizeof(pre));
int h=0,t=0;
q[h++]=s; flow[s]=0x7fffffff;
pre[s]=s; flow[des]=0;
while (h!=t)
{
int u=q[t];
if (u==des) break;
for (int v=1;v<=m;v++) if (a[u][v]>0 && !pre[v])
{
q[h++]=v; pre[v]=u;
flow[v]=min(flow[u],a[u][v]);
}
t++;
}
return flow[des];
}

int maxflow(int s,int des)
{
int t,ans=0;
while(t=bfs(s,des),t!=0)
{
for (int i=des;i!=s;i=pre[i])
{
a[pre[i]][i]-=t;
a[i][pre[i]]+=t;
}
ans+=t;
}
return ans;
}

int main()
{
while (scanf("%d%d",&n,&m)!=EOF)
{
memset(a,0,sizeof(a));
for (int i=1;i<=n;i++)
{
scanf("%d%d%d",&u,&v,&dist);
a[u][v]+=dist;
}
int ans=maxflow(1,m);
printf("%d\n",ans);
}
return 0;
}