最大流DFS（EK）算法模板

来源：互联网发布：ubuntu 安装lnmp 编辑：程序博客网时间：2024/05/29 11:42
#include <iostream>#include <cstdio>#include <cstring>#include <algorithm>#include <cmath>#include <vector>#define maxn 1000#define inf 0x3f3f3f3fusing namespace std;struct edge//数据结构{    int en,flow,rev;};vector <edge> v[maxn];int vis[maxn];void addedge(int st,int en,int flow)//加边{    edge save;    save.en=en;save.flow=flow;save.rev=v[en].size();    v[st].push_back(save);    save.en=st;save.flow=0;save.rev=v[st].size()-1;    v[en].push_back(save);    return;}int dfs(int st,int en,int flow){    if (st==en) return flow;    vis[st]=1;    for (int k=0;k<v[st].size();k++)    {        edge &save=v[st][k];        if ((!vis[save.en])&&(save.flow>0))        {            int d=dfs(save.en,en,min(flow,save.flow));            if (d>0)            {                save.flow-=d;                v[save.en][save.rev].flow+=d;                return min(flow,d);            }        }    }    return 0;}int max_flow(int st,int en)//求最大流{    int sum(0);    while(1)    {        memset(vis,0,sizeof(vis));        int flow(0);        flow=dfs(st,en,inf);        if (flow<=0) break;        else sum+=flow;    }    return sum;}int main(){    int n,t,m,Case;    Case=0;    scanf("%d",&t);    while(t--)    {        scanf("%d %d",&m,&n);        for (int k=1;k<=n;k++)            v[k].clear();        for (int k=1;k<=n;k++)        {            int st,en,flow;            scanf("%d %d %d",&st,&en,&flow);            addedge(st,en,flow);        }        Case++;        printf("Case %d: %d\n",Case,max_flow(1,m));    }    return 0;}
阅读全文
0 0