uva820 Internet Bandwidth

就是模板...

#include<cstdio>
#include<cstring>
#include<vector>
#include<queue>
#include<algorithm>
#include<cmath>
using namespace std;
const int maxn = 110;
#define inf 1<<30
int n;
int a[maxn],p[maxn];
struct edge
{
    int from,to,w,cap,flow;
    edge(int from,int to,int cap,int flow):from(from),to(to),cap(cap),flow(flow){
    }
};
vector<edge> edges;
vector<int> g[maxn];
void init(int k)
{
            for(int i=0;i<=k;i++)g[i].clear();
        edges.clear();
}

void addedge(int from,int to,int cap)
{
    edges.push_back(edge(from,to,cap,0));
    edges.push_back(edge(to,from,cap,0));
    int m=edges.size();
    g[from].push_back(m-2);
    g[to].push_back(m-1);
}
int Max_flow(int s,int t)
{
    int flow=0;
    while(1)
    {
        queue<int> q;
        memset(a,0,sizeof(a));
        q.push(s);
        a[s]=inf;
        while(!q.empty())
        {
            int x = q.front();q.pop();
            for(int i=0;i<g[x].size();i++)
            {
                edge &e=edges[g[x][i]];
                if(!a[e.to]&&e.cap>e.flow)
                {
                    p[e.to]=g[x][i];
                    a[e.to]= min(a[x],e.cap-e.flow);
                    q.push(e.to);
                }
            }
            if(a[t])break;
        }
        if(!a[t])break;
        for(int i=t;i!=s;i=edges[p[i]].from)
        {
            edges[p[i]].flow+=a[t];
            edges[p[i]^1].flow-=a[t];
        }
        flow+=a[t];
    }
    return flow;
}
int main()
{
    int cas = 0;
    while(scanf("%d",&n)&&n)
    {
        int s,t,c;
        int u,v,cap;
        init(n);
        scanf("%d%d%d",&s,&t,&c);
        for(int i=0;i<c;i++)
        {
            scanf("%d%d%d",&u,&v,&cap);
            addedge(u,v,cap);
        }
        printf("Network %d
The bandwidth is %d.

",++cas,Max_flow(s,t));
    }
}