Kruskal 2015百度之星初赛2 HDOJ 5253 连接的管道

题目传送门

 /*
     最小生成树(Kruskal)：以权值为头，带入两个端点，自然的排序;感觉结构体的并查集很好看
     注意：题目老头要的是两个农田的高度差，中文水平不好，题意理解成和平均值的高度差！
 */
 #include <cstdio>
 #include <algorithm>
 #include <cstring>
 #include <cmath>
 #include <vector>
 #include <queue>
 #include <set>
 using namespace std;

 const int MAXN = 1e3 + ;
 const int MAXM = 1e2 + ;
 const int INF = 0x3f3f3f3f;
 int n, m;
 int a[MAXN][MAXN];
 vector<pair<int, int> > G[MAXM];
 struct UF
 {
     int rt[MAXN*MAXN];
     void init(void)    {memset (rt, -, sizeof (rt));}

     int Find(int x)    {return (rt[x] == -) ? x : rt[x] = Find (rt[x]);}

     void Union(int x, int y)
     {
         x = Find (x);    y = Find (y);
         if (x > y)    rt[y] = x;
         else if (x < y)    rt[x] = y;
     }

     bool same(int x, int y)    {return Find (x) == Find (y);}
 }uf;

 int Kruskal(void)
 {
     uf.init ();
     int ans = ;
     for    (int i=; i<=; ++i)
     {
         for (int j=; j<G[i].size (); ++j)
         {
             int u = G[i][j].first;    int v = G[i][j].second;
             if (!uf.same (u, v))    {uf.Union (u, v);    ans += i;}
         }
     }

     return ans;
 }

 int get_id(int i, int j)    {return (i - ) * m + j;}

 int main(void)        //2015百度之星初赛2 HDOJ 5253 连接的管道
 {
     int t, cas = ;    scanf ("%d", &t);
     while (t--)
     {
         scanf ("%d%d", &n, &m);
         for (int i=; i<=; ++i)    G[i].clear ();

         for (int i=; i<=n; ++i)
         {
             for (int j=; j<=m; ++j)
             {
                 scanf ("%d", &a[i][j]);
                 if (i > )    {G[abs (a[i][j] - a[i-][j])].push_back (make_pair (get_id (i, j), get_id (i-, j)));}
                 if (j > )    {G[abs (a[i][j] - a[i][j-])].push_back (make_pair (get_id (i, j), get_id (i, j-)));}
             }
         }

         printf ("Case #%d:\n", ++cas);
         printf ("%d\n", Kruskal ());
     }

     return ;
 }

 /*
 2
 4  3
 9 12 4
 7 8 56
 32 32 43
 21 12 12
 2  3
 34 56 56
 12 23 4
 */