【wikioi1993】草地排水

来源：互联网发布：云购cms 编辑：程序博客网时间：2024/04/26 19:23
#include<iostream>#include<cstdio>#include<cstring>#define INF 0x7fffffffusing namespace std;struct data{int to,next,v;}e[402];int n,m,ne=1,ans;int h[201],q[201],head[201];void insert(int u,int v,int w){     ne++;     e[ne].to=v;e[ne].v=w;     e[ne].next=head[u];     head[u]=ne;     ne++;     e[ne].to=u;     e[ne].next=head[v];     head[v]=ne; }bool bfs(){     memset(h,-1,sizeof(h));     int t=0,w=1,i,now;     q[0]=1;h[1]=0;     while(t<w)     {               now=q[t++];i=head[now];               while(i)               {                       if(e[i].v&&h[e[i].to]==-1)                       {h[e[i].to]=h[now]+1;q[w++]=e[i].to;}                       i=e[i].next;                       }               }     if(h[n]==-1)return 0;     return 1; }int dfs(int x,int f){    if(x==n)return f;    int i=head[x],w,used=0;    while(i)    {            if(e[i].v&&h[e[i].to]==h[x]+1)            {                w=f-used;                w=dfs(e[i].to,min(e[i].v,w));                used+=w;                e[i].v-=w;                e[i|1].v+=w;                if(used==f)return f;                }            i=e[i].next;            }    if(!used)h[x]=-1;    return used;}void dinic(){while(bfs())ans+=dfs(1,INF);}int main(){    scanf("%d%d",&m,&n);    for(int i=1;i<=m;i++)    {            int u,v,w;            scanf("%d%d%d",&u,&v,&w);            insert(u,v,w);            }    dinic();    printf("%d",ans);    return 0;}
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