最小费用最大流模板

来源：互联网发布：mem 知乎编辑：程序博客网时间：2024/06/10 12:35

#include<bits/stdc++.h>#define ll long long#define inf 0x3f3f3f3fusing namespace std;const int MAXN=110;const int MAXM=100010;int head[MAXN],pre[MAXN],dis[MAXN],book[MAXN];int cnt=0,N;//N为点数 struct node{int to,next,cap,flow,cost;}edge[MAXM];void init(){cnt=0;memset(head,-1,sizeof(head));}void addedge(int u,int v,int cap,int cost){edge[cnt].to=v;edge[cnt].cap=cap;edge[cnt].flow=0;edge[cnt].cost=cost;edge[cnt].next=head[u];head[u]=cnt++;edge[cnt].to=u;edge[cnt].cap=0;edge[cnt].flow=0;edge[cnt].cost=-cost;edge[cnt].next=head[v];head[v]=cnt++;}bool spfa(int s,int t){queue<int>q;while(!q.empty())q.pop();for(int i=0;i<=N;i++){dis[i]=inf;pre[i]=-1;book[i]=0;}dis[s]=0;book[s]=1;q.push(s);while(!q.empty()){int u=q.front();q.pop();book[u]=0;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(!book[v]){book[v]=1;q.push(v);}} } }return pre[t]!=-1;}int min_cost_max_flow(int s,int t,int &cost){int flow=0;cost=0;while(spfa(s,t)){int temp=inf;for(int i=pre[t];i!=-1;i=pre[edge[i^1].to])temp=min(temp,edge[i].cap-edge[i].flow);for(int i=pre[t];i!=-1;i=pre[edge[i^1].to]){edge[i].flow+=temp;edge[i^1].flow-=temp;cost+=edge[i].cost*temp;}flow+=temp;}return flow;}

上面是自己写的，下面是从网上扒的用结构体封装好的。

#include<iostream>#include<algorithm>#include<string>#include<sstream>#include<set>#include<vector>#include<stack>#include<map>#include<queue>#include<deque>#include<cstdlib>#include<cstdio>#include<cstring>#include<cmath>#include<ctime>#include<functional>using namespace std;#define N 1000#define INF 100000000struct Edge{    int from,to,cap,flow,cost;    Edge(int u,int v,int ca,int f,int co):from(u),to(v),cap(ca),flow(f),cost(co){};};struct MCMF{    int n,m,s,t;    vector<Edge> edges;    vector<int> G[N];    int inq[N];//是否在队列中    int d[N];//距离    int p[N];//上一条弧    int a[N];//可改进量    void init(int n)//初始化    {        this->n=n;        for(int i=0;i<n;i++)            G[i].clear();        edges.clear();    }    void addedge(int from,int to,int cap,int cost)//加边    {        edges.push_back(Edge(from,to,cap,0,cost));        edges.push_back(Edge(to,from,0,0,-cost));        int m=edges.size();        G[from].push_back(m-2);        G[to].push_back(m-1);    }    bool SPFA(int s,int t,int &flow,int &cost)//寻找最小费用的增广路，使用引用同时修改原flow,cost    {        for(int i=0;i<n;i++)            d[i]=INF;        memset(inq,0,sizeof(inq));        d[s]=0;inq[s]=1;p[s]=0;a[s]=INF;        queue<int> Q;        Q.push(s);        while(!Q.empty())        {            int u=Q.front();            Q.pop();            inq[u]--;            for(int i=0;i<G[u].size();i++)            {                Edge& e=edges[G[u][i]];                if(e.cap>e.flow && d[e.to]>d[u]+e.cost)//满足可增广且可变短                {                    d[e.to]=d[u]+e.cost;                    p[e.to]=G[u][i];                    a[e.to]=min(a[u],e.cap-e.flow);                    if(!inq[e.to])                    {                        inq[e.to]++;                        Q.push(e.to);                    }                }            }        }        if(d[t]==INF) return false;//汇点不可达则退出        flow+=a[t];        cost+=d[t]*a[t];        int u=t;        while(u!=s)//更新正向边和反向边        {            edges[p[u]].flow+=a[t];            edges[p[u]^1].flow-=a[t];            u=edges[p[u]].from;        }        return true;    }    int MincotMaxflow(int s,int t)    {        int flow=0,cost=0;        while(SPFA(s,t,flow,cost));        return cost;    }};int main(){    MCMF mcmf;    return 0;}

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