POJ 1459 Power Network 最大流

#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;
}