POJ 1273&Dinic解决

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题目链接 http://poj.org/problem?id=1273
#include<iostream>using namespace std;#include<queue>#include<vector>#include<cstring>#include<algorithm>#include<deque>#define INFINITE 0x7fffffint G[300][300];bool Visited[300];int Layer[300];int n,m; //1是源点 m是汇点bool CountLayer(){    int layer=0;    deque<int>q;    memset(Layer,0xff,sizeof(Layer));    Layer[1]=0;    q.push_back(1);    while (!q.empty())    {        int v=q.front();        q.pop_front();        for (int j=1;j<=m;j++)        {            if (G[v][j]>0&&Layer[j]==-1)            {                Layer[j]=Layer[v]+1;                if (j==m)                    return true;                else                    q.push_back(j);            }        }    }    return false;}int Dinic(){    int i;    int s;    int nMaxFlow=0;    deque<int>q;    while (CountLayer())    {        q.push_back(1);        memset(Visited,0,sizeof(Visited));        Visited[1]=1;        while (!q.empty())        {            int nd=q.back();            if (nd==m)            {                //source                int nMinC=INFINITE;                int nMinC_vs;                for (i=1;i<q.size();i++)                {                    int vs=q[i-1];                    int ve=q[i];                    if (G[vs][ve]>0)                    {                        if (nMinC>G[vs][ve])                        {                            nMinC=G[vs][ve];                            nMinC_vs=vs;                        }                    }                }                nMaxFlow+=nMinC;                for (i=1;i<q.size();i++)                {                    int vs=q[i-1];                    int ve=q[i];                    G[vs][ve]-=nMinC; //修改边容量                    G[ve][vs]+=nMinC; //添加反向边                }                while (!q.empty()&&q.back()!=nMinC_vs)                {                    Visited[q.back()]=0;                    q.pop_back();                }            }            else            {                for (i=1;i<=m;i++)                {                    if (G[nd][i]>0&&Layer[i]==Layer[nd]+1&&!Visited[i])                    {                        Visited[i]=1;                        q.push_back(i);                        break;                    }                }                if (i>m)                    q.pop_back();            }        }    }    return nMaxFlow;}int main(){    while (cin>>n>>m)    {        int i,j,k;        int s,e,c;        memset(G,0,sizeof(G));        for (int i=0;i<n;i++)        {            cin>>s>>e>>c;            G[s][e]+=c;        }        cout<<Dinic()<<endl;    }    return 0;}
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