網路流模板

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最大流,ISAP，抄的（http://www.cnblogs.com/wally/p/3274438.html）改了下。。

#include<cstdio>#include<cstring>#include<queue>#include<algorithm>using namespace std;#define INF (1<<30)#define MAXN 111#define MAXM 2222struct Edge{    int v,cap,flow,next;}edge[MAXM];int vs,vt,NE,NV;int head[MAXN];void addEdge(int u,int v,int cap){    edge[NE].v=v; edge[NE].cap=cap; edge[NE].flow=0;    edge[NE].next=head[u]; head[u]=NE++;    edge[NE].v=u; edge[NE].cap=0; edge[NE].flow=0;    edge[NE].next=head[v]; head[v]=NE++;}int level[MAXN];int gap[MAXN];void bfs(){    memset(level,-1,sizeof(level));    memset(gap,0,sizeof(gap));    level[vt]=0;    gap[level[vt]]++;    queue<int> que;    que.push(vt);    while(!que.empty()){        int u=que.front(); que.pop();        for(int i=head[u]; i!=-1; i=edge[i].next){            int v=edge[i].v;            if(level[v]!=-1) continue;            level[v]=level[u]+1;            gap[level[v]]++;            que.push(v);        }    }}int pre[MAXN];int cur[MAXN];int ISAP(){    bfs();    memset(pre,-1,sizeof(pre));    memcpy(cur,head,sizeof(head));    int u=pre[vs]=vs,flow=0,aug=INF;    gap[0]=NV;    while(level[vs]<NV){        bool flag=false;        for(int &i=cur[u]; i!=-1; i=edge[i].next){            int v=edge[i].v;            if(edge[i].cap!=edge[i].flow && level[u]==level[v]+1){                flag=true;                pre[v]=u;                u=v;                //aug=(aug==-1?edge[i].cap:min(aug,edge[i].cap));                aug=min(aug,edge[i].cap-edge[i].flow);                if(v==vt){                    flow+=aug;                    for(u=pre[v]; v!=vs; v=u,u=pre[u]){                        edge[cur[u]].flow+=aug;                        edge[cur[u]^1].flow-=aug;                    }                    //aug=-1;                    aug=INF;                }                break;            }        }        if(flag) continue;        int minlevel=NV;        for(int i=head[u]; i!=-1; i=edge[i].next){            int v=edge[i].v;            if(edge[i].cap!=edge[i].flow && level[v]<minlevel){                minlevel=level[v];                cur[u]=i;            }        }        if(--gap[level[u]]==0) break;        level[u]=minlevel+1;        gap[level[u]]++;        u=pre[u];    }    return flow;}

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最小費用最大流

#include<cstdio>#include<cstring>#include<queue>#include<algorithm>using namespace std;#define INF (1<<30)#define MAXN 111#define MAXM 2222struct Edge{    int u,v,cap,cost,next;}edge[MAXM];int head[MAXN];int NV,NE,vs,vt;void addEdge(int u,int v,int cap,int cost){    edge[NE].u=u; edge[NE].v=v; edge[NE].cap=cap; edge[NE].cost=cost;    edge[NE].next=head[u]; head[u]=NE++;    edge[NE].u=v; edge[NE].v=u; edge[NE].cap=0; edge[NE].cost=-cost;    edge[NE].next=head[v]; head[v]=NE++;}bool vis[MAXN];int d[MAXN],pre[MAXN];bool SPFA(){    for(int i=0;i<NV;++i){        vis[i]=0;        d[i]=INF;    }    vis[vs]=1;    d[vs]=0;    queue<int> que;    que.push(vs);    while(!que.empty()){        int u=que.front(); que.pop();        for(int i=head[u]; i!=-1; i=edge[i].next){            int v=edge[i].v;            if(edge[i].cap && d[v]>d[u]+edge[i].cost){                d[v]=d[u]+edge[i].cost;                pre[v]=i;                if(!vis[v]){                    vis[v]=1;                    que.push(v);                }            }        }        vis[u]=0;    }    return d[vt]!=INF;}int MCMF(){    int res=0;    while(SPFA()){        int flow=INF,cost=0;        for(int u=vt; u!=vs; u=edge[pre[u]].u){            flow=min(flow,edge[pre[u]].cap);        }        for(int u=vt; u!=vs; u=edge[pre[u]].u){            edge[pre[u]].cap-=flow;            edge[pre[u]^1].cap+=flow;            cost+=flow*edge[pre[u]].cost;        }        res+=cost;    }    return res;}

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網路流模板