hdu_2236

 1 // hdu2236
 2 // Graph Match  binary search + enumeration + bipartite
 3 // Dec.26 2014
 4
 5 #include <cstdio>
 6 #include <cstring>
 7 #include <algorithm>
 8
 9 #define MaxN 111
10 #define ACCEPT
11
12 int G[MaxN][MaxN], T, n, max_edge, min_edge, l, r, mid, enum_edge, gx[MaxN], gy[MaxN];
13 bool vis[MaxN], is_match;
14
15 bool dfs(int u)
16 {
17     for(int i = 1; i <= n; ++i){
18         if(G[u][i] >= enum_edge && G[u][i] <= enum_edge + mid && vis[i] == false){
19             vis[i] = true;
20             if(gy[i] == -1 || dfs(gy[i]) == true){
21                 gy[i] = u;
22                 gx[u] = i;
23                 return true;
24             }
25         }
26     }
27     return false;
28 }
29
30 bool hungry()
31 {
32     memset(gx, -1, sizeof(gx));
33     memset(gy, -1, sizeof(gy));
34     for(int i = 1; i <= n; ++i){
35         memset(vis, false, sizeof(vis));
36         if(dfs(i) == false)
37             return false;
38     }
39 }
40
41 int main(int argc, char const *argv[])
42 {
43     #ifndef ACCEPT
44         freopen("in.txt","r",stdin);
45     #endif
46     scanf("%d", &T);
47     while(T--){
48         // input , get the max num and min num
49         max_edge = -1;
50         min_edge = 101;
51         scanf("%d", &n);
52         for(int i = 1; i <= n; ++i){
53             for(int j = 1; j <= n; ++j){
54                 scanf("%d", &G[i][j]);
55                 max_edge = std::max(G[i][j], max_edge);
56                 min_edge = std::min(G[i][j], min_edge);
57             }
58         }
59         //
60         l = 0;
61         r = max_edge - min_edge;
62         while(true){
63             mid  = (l + r) >> 1;
64             is_match = false;
65             for(enum_edge = min_edge; enum_edge + mid <= max_edge; ++enum_edge){
66                 if(hungry() == true){
67                     is_match = true;
68                     break;
69                 }
70             }
71             if(is_match == true)
72                 r = mid;
73             if(l == mid)
74                 break;
75             if(is_match == false)
76                 l = mid;
77         }
78         printf("%d\n", r);
79     }
80     return 0;
81 }