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  • 模板

    #include<bits/stdc++.h>
    using namespace std;
    
    const int MAXN=10000;
    const int MAXM=100000;
    const int INF=0x3f3f3f3f;
    struct Edge{
        int to,next,cap,flow,cost;
    }edge[MAXM];
    int head[MAXN],tol;
    int pre[MAXN],dis[MAXN];
    bool vis[MAXN];
    
    void init(){
        tol=0;
        memset(head,-1,sizeof(head));
    }
    
    void addedge(int u,int v,int cap,int cost){
        edge[tol].to=v;
        edge[tol].cap=cap;
        edge[tol].cost=cost;
        edge[tol].flow=0;
        edge[tol].next=head[u];
        head[u]=tol++;
    
        edge[tol].to=u;
        edge[tol].cap=0;
        edge[tol].cost=-cost;
        edge[tol].flow=0;
        edge[tol].next=head[v];
        head[v]=tol++;
    }
    
    bool spfa(int s,int t){
        queue<int> q;
        memset(dis,INF,sizeof(dis));
        memset(vis,false,sizeof(vis));
        memset(pre,-1,sizeof(pre));
    
        dis[s]=0;
        vis[s]=true;
        q.push(s);
        while(!q.empty()){
            int u=q.front();
            q.pop();
            vis[u]=false;
            for(int i=head[u];i!=-1;i=edge[i].next){
                int v=edge[i].to;
                if(edge[i].cap>edge[i].flow&&dis[v]>dis[u]+edge[i].cost){
                    dis[v]=dis[u]+edge[i].cost;
                    pre[v]=i;
                    if(!vis[v]){
                        vis[v]=true;
                        q.push(v);
                    }
                }
            }
        }
        if(pre[t]==-1)
            return false;
        else
            return true;
    }
    
    int minCostMaxFlow(int s,int t,int &cost){
        int flow=0;
        cost=0;
        while(spfa(s,t)){
            int Min=INF;
            for(int i=pre[t];i!=-1;i=pre[edge[i^1].to]){
                if(Min>edge[i].cap-edge[i].flow)
                    Min=edge[i].cap-edge[i].flow;
            }
            for(int i=pre[t];i!=-1;i=pre[edge[i^1].to]){
                edge[i].flow+=Min;
                edge[i^1].flow-=Min;
                cost+=edge[i].cost*Min;
            }
            flow+=Min;
        }
        return flow;
    }
    
    int main(){
        int N,M,S,T;
        scanf("%d%d%d%d",&N,&M,&S,&T);
        init();
        while(M--){
            int u,v,cap,cost;
            scanf("%d%d%d%d",&u,&v,&cap,&cost);
            addedge(u,v,cap,cost);
        }
        int cost=0;
        int flow=minCostMaxFlow(S,T,cost);
    
        printf("%d %d
    ",flow,cost);
    }
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  • 原文地址:https://www.cnblogs.com/Yinku/p/10619057.html
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