按照电站发电(从源点到电站),消费者消费(从消费者到汇点)的想法构建网络,以下是EK解法
//网络流EK算法 //Time:922Ms memory:224K #include<iostream> #include<cstring> #include<cstdio> #include<algorithm> #include<queue> using namespace std; #define MAX 105 #define INF 0x3f3f3f3f int n,np,nc,m; int s,t; int res[MAX][MAX]; //残留网络 int pre[MAX]; bool bfs() { memset(pre,-1,sizeof(pre)); queue<int> q; q.push(s); pre[s] = 0; while(!q.empty()){ int cur = q.front(); q.pop(); for(int i = 1; i <= t; i++) { if(pre[i] == -1 && res[cur][i]) { pre[i] = cur; if(i == t) return true; q.push(i); } } } return false; } int EK() { int maxFlow = 0; while(bfs()){ int alpha = INF; //最小可改进量 for(int i = t; i != s; i = pre[i]) alpha = min(alpha, res[pre[i]][i]); for(int i = t; i != s; i = pre[i]) { res[pre[i]][i] -= alpha; res[i][pre[i]] += alpha; } maxFlow += alpha; } return maxFlow; } int main() { //freopen("in.txt", "r", stdin); while(~scanf("%d%d%d%d", &n,&np,&nc,&m)){ s = 0; t = n+2; memset(res,0,sizeof(res)); int a,b,c; while(m--){ scanf(" (%d,%d)%d", &a,&b,&c); res[a+1][b+1] = c; } for(int i = 0; i < np; i++) { //电站 scanf(" (%d)%d", &b,&c); res[s][b+1] = c; } for(int i = 0; i < nc; i++) { //消费 scanf(" (%d)%d", &a,&c); res[a+1][t] = c; } printf("%d\n", EK()); } return 0; }