Poj1273最大流 裸题模板

题目链接

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http://poj.org/problem?id=1273
 没啥好说直接模板

#include <iostream>#include <cstdio>#include <algorithm>#include <cstring>#include <queue>#include <vector>using namespace std;int n, m;const int maxn = 250;const int INF = 0x3f3f3f3f;struct Edge{    int from, to, cap, flow;    Edge(int u, int v, int c, int f):from(u), to(v), cap(c), flow(f) {}};struct EdmondsKarp{    vector<int>G[maxn];    vector<Edge>edges;    int a[maxn];    int p[maxn];    void init(int n)    {        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));        int 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(;;)        {            queue<int> Q;            Q.push(s);            memset(a, 0, sizeof(a));            a[s] = INF;            while(!Q.empty())            {                int x = Q.front();                Q.pop();                for(int i = 0;i < (int)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;    }}ek;int main(){    while(cin>>n>>m)    {        ek.init(m);        for(int i = 1;i <= n;i++)        {            int a, b, c;            cin>>a>>b>>c;            a--;            b--;            ek.AddEdge(a, b, c);        }        cout<<ek.MaxFlow(0, m - 1)<<endl;    }    return 0;}