HDU 3435 KM A new Graph Game

和HDU 3488一样的，只不过要判断一下是否有解。

  1 #include <iostream>
  2 #include <cstdio>
  3 #include <cstring>
  4 #include <algorithm>
  5 #include <vector>
  6 using namespace std;
  7 
  8 const int maxn = 1000 + 10;
  9 const int INF = 0x3f3f3f3f;
 10 
 11 int n, m;
 12 
 13 int W[maxn][maxn], lft[maxn];
 14 int slack[maxn];
 15 int Lx[maxn], Ly[maxn];
 16 bool S[maxn], T[maxn];
 17 
 18 bool match(int u)
 19 {
 20     S[u] = true;
 21     for(int v = 1; v <= n; v++) if(!T[v])
 22     {
 23         int t = Lx[u] + Ly[v] - W[u][v];
 24         if(0 == t)
 25         {
 26             T[v] = true;
 27             if(!lft[v] || match(lft[v]))
 28             {
 29                 lft[v] = u;
 30                 return true;
 31             }
 32         }
 33         else slack[v] = min(slack[v], t);
 34     }
 35 
 36     return false;
 37 }
 38 
 39 void update()
 40 {
 41     int a = INF;
 42     for(int i = 1; i <= n; i++) if(!T[i]) a =  min(a, slack[i]);
 43     for(int i = 1; i <= n; i++)
 44     {
 45         if(S[i]) Lx[i] -= a;
 46 
 47         if(T[i]) Ly[i] += a;
 48         else  slack[i] -= a;
 49     }
 50 }
 51 
 52 void KM()
 53 {
 54     memset(Ly, 0, sizeof(Ly));
 55     memset(lft, 0, sizeof(lft));
 56     for(int i = 1; i <= n; i++) Lx[i] = -INF;
 57     for(int i = 1; i <= n; i++)
 58         for(int j = 1; j <= n; j++) Lx[i] = max(Lx[i], W[i][j]);
 59 
 60     for(int i = 1; i <= n; i++)
 61     {
 62         memset(slack, 0x3f, sizeof(slack));
 63         for(;;)
 64         {
 65             memset(S, false, sizeof(S));
 66             memset(T, false, sizeof(T));
 67             if(match(i)) break;
 68             update();
 69         }
 70     }
 71 }
 72 
 73 int main()
 74 {
 75     int T; scanf("%d", &T);
 76     for(int kase = 1; kase <= T; kase++)
 77     {
 78         scanf("%d%d", &n, &m);
 79         for(int i = 1; i <= n; i++)
 80             for(int j = 1; j <= n; j++)
 81                 W[i][j] = -INF;
 82         for(int i = 0; i < m; i++)
 83         {
 84             int u, v, d; scanf("%d%d%d", &u, &v, &d);
 85             if(W[u][v] < -d) W[u][v] = W[v][u] = -d;
 86         }
 87 
 88         KM();
 89 
 90         bool ok = true;
 91         int ans = 0;
 92         for(int i = 1; i <= n; i++)
 93         {
 94             if(W[lft[i]][i] == -INF) { ok = false; break; }
 95             ans += W[lft[i]][i];
 96         }
 97         printf("Case %d: ", kase);
 98         if(!ok) puts("NO");
 99         else printf("%d\n", -ans);
100     }
101 
102     return 0;
103 }