【HDOJ】3549 Flow Problem

网络流基础题目，Edmonds_Karp可解。

 /* 3549 */
 #include <iostream>
 #include <string>
 #include <map>
 #include <queue>
 #include <set>
 #include <stack>
 #include <vector>
 #include <deque>
 #include <algorithm>
 #include <cstdio>
 #include <cmath>
 #include <ctime>
 #include <cstring>
 #include <climits>
 #include <cctype>
 #include <cassert>
 #include <functional>
 using namespace std;

 #define rep(i, a, n)     for (int i=a;i<n;++i)
 #define per(i, a, n)     for (int i=n-1;i>=a;--i)
 #define pb                 push_back
 #define mp                 make_pair
 #define all(x)             (x).begin(),(x).end()
 #define SZ(x)             ((int)(x).size())
 #define lson            l, mid, rt<<1
 #define rson            mid+1, r, rt<<1|1

 const int maxn = ;
 int F[maxn][maxn];
 int P[maxn], a[maxn];
 int n, m, ans;
 int s, t;

 bool bfs() {
     int u, v;
     queue<int> Q;

     memset(a, , sizeof(a));
     a[s] = INT_MAX;
     Q.push(s);
     P[s] = s;

     while (!Q.empty()) {
         u = Q.front();
         Q.pop();
         for (v=; v<=n; ++v) {
             if (!a[v] && F[u][v]) {
                 P[v] = u;
                 Q.push(v);
                 a[v] = min(a[u], F[u][v]);
             }
         }
     }

     return a[t] == ;
 }

 void Edmonds_Karp() {
     int u, v;

     s = ;
     t = n;
     ans = ;

     while (true) {
         if (bfs())
             break;
         for (u=t; u!=s; u=P[u]) {
             F[u][P[u]] += a[t];
             F[P[u]][u] -= a[t];
         }
         ans += a[t];
     }
 }

 int main() {
     int i, j, k;
     int t, tt;

     #ifndef ONLINE_JUDGE
         freopen("data.in", "r", stdin);
         freopen("data.out", "w", stdout);
     #endif

     scanf("%d", &tt);
     for (t=; t<=tt; ++t) {
         scanf("%d %d", &n, &m);
         memset(F, , sizeof(F));
         while (m--) {
             scanf("%d %d %d", &i, &j, &k);
             F[i][j] += k;
         }
         Edmonds_Karp();
         printf("Case %d: %d\n", t, ans);
     }

     #ifndef ONLINE_JUDGE
         printf("time = %d.\n", (int)clock());
     #endif

     return ;
 }