POJ-1273 Drainage Ditches 最大流裸题

//STATUS:C++_AC_0MS_760KB
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<math.h>
#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<queue>
#include<stack>
#include<map>
using namespace std;
#define LL long long
#define Max(a,b) ((a)>(b)?(a):(b))
#define Min(a,b) ((a)<(b)?(a):(b))
#define mem(a,b) memset(a,b,sizeof(a))
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
const int MAX=210,INF=0x3f3f3f3f;

struct Edge{
int from,to,cap,flow;
};

vector<Edge> edge;
vector<int> g[MAX];
int d[MAX],cur[MAX],vis[MAX];
int n,m,s,t;

int bfs()
{
int x,i;
queue<int> q;
q.push(s);
mem(vis,0);
d[s]=0;
vis[s]=1;
while(!q.empty())
{
x=q.front();q.pop();
for(i=0;i<g[x].size();i++){
Edge& e=edge[g[x][i]];
if(!vis[e.to] && e.cap>e.flow){
vis[e.to]=1;
d[e.to]=d[x]+1;
q.push(e.to);
}
}
}
return vis[t];
}

int dfs(int x,int a)
{
if(x==t || a==0)return a;
int f,flow=0;
for(int& i=cur[x];i<g[x].size();i++){
Edge& e=edge[g[x][i]];
if(d[x]+1==d[e.to] && (f=dfs(e.to,Min(a,e.cap-e.flow)))>0){
e.flow+=f;
edge[g[x][i]^1].flow-=f;
flow+=f;
a-=f;
if(!a)break;
}
}
return flow;
}

int dinic()
{
int flow=0;
while(bfs()){
mem(cur,0);
flow+=dfs(s,INF);
}
return flow;
}

int main()
{
//   freopen("in.txt","r",stdin);
int i,j,u,v,val,ans;
while(~scanf("%d%d",&m,&n))
{
s=1,t=n;
for(i=1;i<=n;i++)g[i].clear();
edge.clear();
m<<=1;
for(i=0;i<m;i+=2){
scanf("%d%d%d",&u,&v,&val);
edge.push_back((Edge){u,v,val,0});
edge.push_back((Edge){v,u,0,0});
g[u].push_back(i);
g[v].push_back(i+1);
}

ans=dinic();

printf("%d\n",ans);
}
return 0;
}