最大流模板题,用EK算法。
#include <iostream> #include <cstdio> #include <cstring> #include <queue> using namespace std; #define INF 9999999 int map[260][260],flow[260][260]; int EdmondsKarp(int sta,int tar) { int cnt,t,i,f[260],pr[260]; queue<int> q; cnt=0; memset(flow,0,sizeof(flow)); while (1) { memset(f,0,sizeof(f)); q.push(sta); f[sta]=INF; while (!q.empty()) { t=q.front(); q.pop(); for (i=sta; i<=tar; i++) { if (f[i] == 0 && map[t][i] > flow[t][i]) { q.push(i); f[i]=f[t] < map[t][i]-flow[t][i]?f[t]:map[t][i]-flow[t][i]; pr[i]=t; } } } if (f[tar] == 0) break; for (i=tar; i!=sta; i=pr[i]) { flow[pr[i]][i]+=f[tar]; flow[i][pr[i]]-=f[tar]; } cnt+=f[tar]; } return cnt; } int main() { int n,m,i,t1,t2,t3,ans; while (cin>>n>>m) { memset(map,0,sizeof(map)); for (i=0; i<n; i++) { cin>>t1>>t2>>t3; map[t1][t2]+=t3; } ans=EdmondsKarp(1,m); printf("%d\n",ans); } }