[HDU 1213]How Many Tables

题目链接:

注意:从1开始循环,一定要循环到n啊(<=n)

 1 #include<iostream>
 2 #include<cstdio>
 3 using namespace std;
 4 
 5 const int maxn = 1010;
 6 int ufs[maxn];
 7 
 8 void Init(int n) {
 9     for(int i = 1;i <= n;i++) {
10         ufs[i] = i;
11     }
12 }
13 
14 int FindRoot(int x) {
15     return ufs[x] == x ? x : ufs[x] = FindRoot(ufs[x]);
16 }
17 
18 bool Merge(int x,int y) {
19     int a = FindRoot(x);
20     int b = FindRoot(y);
21     if(a == b)
22         return false;
23     else
24     {
25         ufs[b] = a;
26         return true;
27     }
28 }
29 
30 int main() {
31     int n,m;
32     int t;
33     scanf("%d",&t);
34     while(t--) {
35         scanf("%d%d",&n,&m);
36         Init(n);
37         int x,y;
38         while(m--) {
39             scanf("%d%d",&x,&y);
40             if(Merge(x,y))
41                 n--;
42         }
43         printf("%d\n",n);
44     }
45     return 0;
46 }