UVA820 Internet Bandwidth

很裸的模版题，就是敲起来稍微麻烦一点。

#include<bits/stdc++.h>
using namespace std;

struct Edge
{
    int v,cap;
};

const int maxn = 101;
vector<Edge> E;
vector<int> G[maxn];
#define PB push_back
void AddEdge(int u,int v,int c)
{
    G[u].PB(E.size());
    E.PB({v,c});
    G[v].PB(E.size());
    E.PB({u,0});
}

int S,T;

bool vis[maxn];
int d[maxn];
bool bfs()
{
    memset(vis,0,sizeof(vis));
    queue<int> q; q.push(S); d[S] = 0; vis[S] = true;
    while(q.size()){
        int u = q.front(); q.pop();
        for(int i = 0; i < G[u].size(); i++){
            Edge &e = E[G[u][i]];
            if(!vis[e.v] && e.cap>0){
                vis[e.v] = true;
                d[e.v] = d[u]+1;
                q.push(e.v);
            }
        }
    }
    return vis[T];
}

int cur[maxn];
int dfs(int u,int a)
{
    if(u == T||!a) return a;
    int flow = 0,f;
    for(int &i = cur[u]; i < G[u].size(); i++){
        Edge &e = E[G[u][i]];
        if(d[e.v] == d[u]+1 && (f = dfs(e.v,min(e.cap,a)))>0){
            flow += f;
            e.cap -= f;
            E[G[u][i]^1].cap += f;
            a -= f;
            if(!a) break;
        }
    }
    return flow;
}

const int INF = 0x3f3f3f3f;
int MaxFlow()
{
    int flow = 0;
    while(bfs()){
        memset(cur,0,sizeof(cur));
        flow += dfs(S,INF);
    }
    return flow;
}

int cap[maxn][maxn];

int main()
{
    //freopen("in.txt","r",stdin);
    int n,kas = 0;
    while(scanf("%d",&n),n){
        for(int i = 1; i <= n; i++) G[i].clear();
        E.clear();
        memset(cap,0,sizeof(cap));
        int m; scanf("%d%d%d",&S,&T,&m);
        while(m--){
            int u,v,c; scanf("%d%d%d",&u,&v,&c);
            cap[u][v] += c;
            cap[v][u] = cap[u][v];
        }
        for(int i = 1; i <= n; i++)
        for(int j = i+1; j <= n; j++) if(cap[i][j]>0){
            AddEdge(i,j,cap[i][j]); AddEdge(j,i,cap[i][j]);
        }
        printf("Network %d\nThe bandwidth is %d.\n\n",++kas,MaxFlow());
    }
    return 0;
}