POJ 1459 Power Network 最大流
建模不难,就读入有点麻烦,无脑拍完dinic 1A happy~
#include <cstdio> #include <cstring> #include <cmath> #include <algorithm> #include <climits> #include <string> #include <iostream> #include <map> #include <cstdlib> #include <list> #include <set> #include <queue> #include <stack> using namespace std; typedef long long LL; const int maxn = 105; int n,np,nc,m; //n节点数目,np电站数目,nc消费者数目,m电线 int cap[maxn][maxn],s,t; //cap 容量,s源点,t汇点 int level[maxn],q[maxn * 2],qs,qe; void input() { memset(cap,0,sizeof(cap)); s = 0; t = n + 1; for(int i = 0;i < m;i++) { int a,b,L; scanf(" (%d,%d)%d",&a,&b,&L); a++; b++; cap[a][b] = L; } for(int i = 0;i < np;i++) { int a,P; scanf(" (%d)%d",&a,&P); a++; cap[s][a] = P; } for(int i = 0;i < nc;i++) { int a,C; scanf(" (%d)%d",&a,&C); a++; cap[a][t] = C; } /* printf("\n%d %d\n",s,t); for(int i = s;i <= t;i++) { for(int j = s;j <= t;j++) { printf("%d ",cap[i][j]); } putchar('\n'); } */ } bool bfs() { qs = qe = 0; q[qe++] = s; memset(level,0,sizeof(level)); level[s] = 1; while(qs < qe) { int v = q[qs++]; if(v == t) break; for(int i = s;i <= t;i++) if(cap[v][i] && !level[i]) { level[i] = level[v] + 1; q[qe++] = i; } } return level[t]; } int dinic(int now,int alpha) { int sum = 0; if(now == t) return alpha; for(int i = s;i <= t;i++) { if(level[i] == level[now] + 1 && alpha && cap[now][i]) { int ret = dinic(i,min(alpha,cap[now][i])); cap[now][i] -= ret; cap[i][now] += ret; alpha -= ret; sum += ret; } } return sum; } void solve() { int ans = 0; while(bfs()) ans += dinic(s,INT_MAX); printf("%d\n",ans); } int main() { while(scanf("%d%d%d%d",&n,&np,&nc,&m) != EOF) { input(); solve(); } return 0; }