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最大流模板(2)
#include <iostream>#include <cstdio>#include <string>#include <cstring>#include <stdlib.h>#include <math.h>#include <ctype.h>#include <queue>#include <map>#include <set>#include <algorithm>using namespace std;const int INF=0x3f3f3f3f;int head[500], source, sink, nv, cnt;int cur[500], num[500], d[500], pre[500];struct node{ int u, v, cap, next;} edge[100000];void add(int u, int v, int cap){ edge[cnt].v=v; edge[cnt].cap=cap; edge[cnt].next=head[u]; head[u]=cnt++; edge[cnt].v=u; edge[cnt].cap=0; edge[cnt].next=head[v]; head[v]=cnt++;}void bfs(){ memset(num,0,sizeof(num)); memset(d,-1,sizeof(d)); queue<int>q; q.push(sink); d[sink]=0; num[0]=1; while(!q.empty()) { int u=q.front(); q.pop(); for(int i=head[u]; i!=-1; i=edge[i].next) { int v=edge[i].v; if(d[v]==-1) { d[v]=d[u]+1; num[d[v]]++; q.push(v); } } }}void isap(){ memcpy(cur,head,sizeof(cur)); int flow=0, u=pre[source]=source, i; bfs(); while(d[source]<nv) { if(u==sink) { int f=INF, pos; for(i=source; i!=sink; i=edge[cur[i]].v) { if(f>edge[cur[i]].cap) { f=edge[cur[i]].cap; pos=i; } } for(i=source; i!=sink; i=edge[cur[i]].v) { edge[cur[i]].cap-=f; edge[cur[i]^1].cap+=f; } flow+=f; u=pos; } for(i=cur[u]; i!=-1; i=edge[i].next) { if(d[edge[i].v]+1==d[u]&&edge[i].cap) break; } if(i!=-1) { cur[u]=i; pre[edge[i].v]=u; u=edge[i].v; } else { if(--num[d[u]]==0) break; int mind=nv; for(i=head[u]; i!=-1; i=edge[i].next) { if(mind>d[edge[i].v]&&edge[i].cap) { mind=d[edge[i].v]; cur[u]=i; } } d[u]=mind+1; num[d[u]]++; u=pre[u]; } } printf("%d\n",flow);}int main(){ int n, m, i, u, v, w, num=0; while(scanf("%d%d",&n,&m)!=EOF) { memset(head,-1,sizeof(head)); cnt=0; source=1; sink=m; nv=sink+1; while(n--) { scanf("%d%d%d",&u,&v,&w); add(u,v,w); } //printf("Case %d: ",num); isap(); } return 0;}
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