网络流模板

标签：acm

#include <bits/stdc++.h>

using namespace std;
#define INF 0x7ffffff
#define maxn 100000

struct Edge
{
    int from, to, cap, flow;
    Edge(int u, int v, int c, int f):from(u), to(v), cap(c), flow(f){}
};

int n, m;
vector<Edge> edges;
vector<int> G[maxn];
int a[maxn];
int p[maxn];

void init()
{
    for(int i=0; i<n; 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, 0, 0));
    m = edges.size();
    G[from].push_back(m-2);
    G[to].push_back(m-1);
}

int Maxflow(int s, int t)
{
    int flow = 0;
    for(;;)
    {
        memset(a, 0, sizeof(a));
        queue<int> Q;
        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 u=t; u!=s; u=edges[p[u]].from)
        {
            edges[p[u]].flow += a[t];
            edges[p[u]^1].flow -= a[t];
        }
        flow += a[t];
    }
    return flow;
}


int main()
{
    int k;
    while(~scanf("%d%d", &n, &k))
    {
        int u, v, cap;
        for(int i=0; i<k; i++)
        {
            scanf("%d%d%d", &u, &v, &cap);
            AddEdge(u, v, cap);
        }
        cout<<Maxflow(0, n-1)<<endl;
    }
    return 0;
}

网络流模板

标签：acm

原文地址：http://blog.csdn.net/dojintian/article/details/45665389