网络流模板(模板题：POJ1273)

模板题：POJ1273

EK:

#include <queue>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
int n,m,jy,map[305][305],c[305][305],a[305],p[305];
bool vis[305];
int M(int e)
{
    int f=0;
    queue<int>q;
    while(1){
        memset(a,0,sizeof(a));
        memset(vis,0,sizeof(vis));
        a[1]=0x3fffffff;vis[1]=1;q.push(1);
        while(!q.empty()){
            jy=q.front();q.pop();
            for(int i=1;i<=e;i++){
                if(!vis[i]&&map[jy][i]-c[jy][i]>0)
                {
                    vis[i]=1;
                    a[i]=min(a[jy],map[jy][i]-c[jy][i]);
                    p[i]=jy;
                    q.push(i);
                }
            }
        }
        if(a[e]==0)break;
        for(int i=e;i!=1;i=p[i]){
            c[i][p[i]]-=a[e];
            c[p[i]][i]+=a[e];
        }
        f+=a[e];
    }
    return f;
}
int main()
{
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        memset(map,0,sizeof(map));
        memset(c,0,sizeof(c));
        memset(p,0,sizeof(p));
        for(int i=1;i<=n;i++)
        {
            register int xx,yy,ee;
            scanf("%d%d%d",&xx,&yy,&ee);
            map[xx][yy]+=ee;
        }
        printf("%d\n",M(m));
    }
}

Dinic：

#include <queue>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
#define N 444
int tot,next[N],first[N],w[N],v[N],n,m,ch[N];
void add(int from,int to,int weight){
    v[tot]=to;w[tot]=weight;
    next[tot]=first[from];
    first[from]=tot++;
}
bool tell(){
    memset(ch,-1,sizeof(ch));
    queue<int> q;
    q.push(1);ch[1]=0;
    while(!q.empty()){
        int t=q.front();q.pop();
        for(int i=first[t];~i;i=next[i])
            if(w[i]&&ch[v[i]]==-1)
                q.push(v[i]),ch[v[i]]=ch[t]+1;
    }
    return ch[n]!=-1;
}
int zeng(int a,int b){
    if(a==n)return b;
    int r=0;
    for(int i=first[a];~i&&b>=r;i=next[i])
        if(ch[a]+1==ch[v[i]]&&w[i]){
            int t=zeng(v[i],min(b-r,w[i]));
            w[i]-=t;w[i^1]+=t;r+=t;
        }
    if(!r)ch[a]=-1;
    return r;
}
int dinic(){
    int ans=0,jy;
    while(tell())while(jy=zeng(1,0x3fffffff))ans+=jy;
    return ans;
}
int main()
{
    while(scanf("%d%d",&m,&n)!=EOF){
        memset(first,-1,sizeof(first));
        register int xx,yy,zz;
        tot=0;
        for(int i=1;i<=m;i++){
            scanf("%d%d%d",&xx,&yy,&zz);
            add(xx,yy,zz);add(yy,xx,0);
        }
        printf("%d\n",dinic());
    }
}