poj 1273 Drainage Ditches_最大流模版

#include <iostream>
#include<cstdio>
#include<queue>
#include<cstring>
using namespace std;
#define INF 0xfffffff
#define N 210
int cap

,flow

;
int pre
,dist
;
int ek(int sta,int end){
int i,curr,sum=0;
memset(flow,0,sizeof(flow));
while(1){
memset(pre,0,sizeof(pre));
memset(dist,0,sizeof(dist));
queue<int> q;
q.push(sta);
dist[sta]=INF;
pre[sta]=sta;
while(!q.empty()){
curr=q.front();
q.pop();
for(i=1;i<=end;i++)
if(!dist[i]&&flow[curr][i]<cap[curr][i]){
dist[i]=min(dist[curr],cap[curr][i]-flow[curr][i]);
pre[i]=curr;
q.push(i);
}
}
if(dist[end]==0)
break;
for(i=end;i!=sta;i=pre[i]){
curr=pre[i];
flow[curr][i]+=dist[end];
flow[i][curr]-=dist[end];
}
sum+=dist[end];
}
return sum;
}

int main(int argc, char** argv) {
int n,m,i,a,b,w;
while(scanf("%d%d",&n,&m)!=EOF){
memset(cap,0,sizeof(cap));
for(i=1;i<=n;i++){
scanf("%d%d%d",&a,&b,&w);
cap[a][b]+=w;
}
printf("%d\n",ek(1,m));
}
return 0;
}

#include<iostream>
#include<cstdio>
#include<cstring>
#include<queue>
using namespace std;
#define N 210
#define INF 0xfffffff
int flow

,dist
,m,n;
int bfs(){
memset(dist,-1,sizeof(dist));
dist[1]=0;
queue<int> q;
q.push(1);
while(!q.empty()){
int k=q.front();
q.pop();
for(int i=1;i<=n;i++){
if(flow[k][i]>0&&dist[i]<0){
dist[i]=dist[k]+1;
q.push(i);
}
}
}
if(dist
>0) return 1;
else return 0;
}
int dfs(int x,int mx){
int i,a;
if(x==n) return mx;
for(i=1;i<=n;i++){
if(flow[x][i]>0&&dist[i]==dist[x]+1&&(a=dfs(i,min(mx,flow[x][i])))){
flow[x][i]-=a;
flow[i][x]+=a;
return a;
}

}
return 0;
}
int main(){
int i,b,a,w,ans,res;
while(scanf("%d%d",&m,&n)!=EOF){
memset(flow,0,sizeof(flow));
for(i=0;i<m;i++){
scanf("%d%d%d",&a,&b,&w);
flow[a][b]+=w;
}
ans=0;
while(bfs())
while(res=dfs(1,INF))
ans+=res;
printf("%d\n",ans);
}
}