二分图最大匹配(匈牙利算法) UVA 10080 Gopher II

 

题目传送门

 1 /*  2  匈牙利算法：这题比UVA_670简单，注意是要被吃的鼠的最少个数，套模板  3 */  4 #include <cstdio>  5 #include <algorithm>  6 #include <cstring>  7 #include <cmath>  8 #include <vector>  9 using namespace std; 10 11 const int MAXN = 1e2 + 10; 12 const int INF = 0x3f3f3f3f; 13 struct P 14 { 15 double x, y; 16 }a[MAXN], b[MAXN]; 17 bool vis[MAXN]; 18 int lk[MAXN]; 19 vector<int> G[MAXN]; 20 21 double get_dis(double x1, double y1, double x2, double y2) 22 { 23 return sqrt ((x1-x2) * (x1-x2) + (y1-y2) * (y1-y2)); 24 } 25 26 bool DFS(int u) 27 { 28 for (int i=0; i<G[u].size (); ++i) 29  { 30 int v = G[u][i]; 31 if (!vis[v]) 32  { 33 vis[v] = true; 34 if (lk[v] == -1 || DFS (lk[v])) 35  { 36 lk[v] = u; return true; 37  } 38  } 39  } 40 41 return false; 42 } 43 44 int hungary(int n) 45 { 46 int res = 0; memset (lk, -1, sizeof (lk)); 47 for (int i=1; i<=n; ++i) 48  { 49 memset (vis, false, sizeof (vis)); 50 if (DFS (i)) res++; 51  } 52 53 return res; 54 } 55 56 int main(void) //UVA 10080 Gopher II 57 { 58 // freopen ("UVA_10080.in", "r", stdin); 59 60 int n, m, s, v; 61 while (scanf ("%d%d%d%d", &n, &m, &s, &v) == 4) 62  { 63 for (int i=1; i<=n; ++i) scanf ("%lf%lf", &a[i].x, &a[i].y); 64 for (int i=1; i<=m; ++i) scanf ("%lf%lf", &b[i].x, &b[i].y); 65 for (int i=1; i<=n; ++i) G[i].clear (); 66 for (int i=1; i<=n; ++i) 67  { 68 for (int j=1; j<=m; ++j) 69  { 70 if (get_dis (a[i].x, a[i].y, b[j].x, b[j].y) <= s * v) G[i].push_back (j); 71  } 72  } 73 74 printf ("%d\n", n - hungary (n)); 75  } 76 77 return 0; 78 }