增广路 EdmondsKarp算法

最大流问题中求解
可以当做模板直接使用

#include 
#include
#include
#include
using namespace std;
 const int maxn=1000+10;
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
#define inf 1000000;
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{
    int n,m;
    vector edges;//正路和逆路 
    vector<int> g[maxn];//邻接表，节点i的第j条边在edges中的序号 
    int a[maxn];//从起点到i的可改进量 
    int p[maxn];
    void init(int n){
        this->n=n;
        for(int i=0;ivoid addedge(int from,int to,int cap,int flow){
        edges.push_back(edge(from,to,cap,0));
        edges.push_back(edge(to,from,0,0));//一般逆路无用，设cap为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;iif(!a[e.to]&&e.cap>e.flow){
                        p[e.to]=g[x][i];
                        a[e.to]=max(a[e.from],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 argc, char** argv) {
    return 0;
}