C - How Many Tables

Posted 2020-12-26 jaydenouyang

 1 #include <cstdio>
 2 #include <cstdlib>
 3 #include <iostream>
 4 #include <algorithm>
 5 #include <cstring>
 6 using namespace std;
 7 
 8 #define MAXN 5000
 9 int fa[MAXN];    //父节点
10 int Rank[MAXN];    //数的高度
11 int ans;
12 
13 void init(int n)    //初始化
14 {
15     for (int i = 0; i < n; i++)
16     {
17         fa[i] = i;    //每个人的根都是自己
18         Rank[i] = 0;    //每颗树的高度都为0
19     }
20 }
21 
22 int find(int x)    //查（查询根节点）
23 {
24     if(fa[x] == x)
25         return x;
26     else
27     {
28         fa[x] = find(fa[x]);    //递归求根节点
29         return fa[x];
30     }
31 }
32 
33 void set_union(int x, int y)    //(并)
34 {
35     x = find(x);
36     y = find(y);
37     if (x == y)
38         return;
39     if (Rank[x] < Rank[y])
40         fa[x] = y;
41     else
42         fa[y] = x;
43     if (Rank[x] == Rank[y])
44         Rank[x]++;    //树的高度加一
45 }
46 
47 bool same(int x, int y)    //判断两个节点是否属于同一个集合
48 {
49     return find(x)==find(y);
50 }
51 
52 int main()
53 {
54     int n, m, t;
55     scanf("%d", &t);
56     while (t--)
57     {
58         scanf("%d %d", &n, &m);
59         memset(fa, 0, sizeof(fa));//对父节点进行清零
60         ans = n;    //最开始的时候ans = 人数
61         init(n);
62         for (int i = 0; i < m; i++)
63         {
64             int x, y;
65             scanf("%d %d", &x, &y);
66             if (same(x, y))
67                 continue;
68             else
69             {
70                 set_union(x, y);
71                 ans--;
72             }
73         }
74         printf("%d
", ans);
75     }
76     //system("pause");
77     return 0;
78 }