并查集

547. 省份数量 - 力扣(LeetCode) (leetcode-cn.com)

 1 class Solution {
 2 public:
 3     vector<int>father;
 4     int find(int x){
 5         if(father[x]==x)
 6             return x;
 7         return find(father[x]);
 8     }
 9     void tunion(int a,int b){
10         father[find(b)] = find(a);
11     }
12     int findCircleNum(vector<vector<int>>& isConnected) {
13         int n = isConnected.size();
14         father = vector<int>(n);
15         for (int i=0;i<n;i++){
16             father[i] = i;
17             for (int j=0;j<i;j++){
18                 if(isConnected[i][j] == 1){
19                     tunion(j,i);
20                 }
21             }
22         }
23         vector<int>vis(n,0);
24         int ans = 0;
25         for(int i=0;i<n;i++){
26             if(vis[i] == 1)
27                 continue ;
28             ans++;vis[i] = 1;
29             for(int j=i+1;j<n;j++){
30                 if(find(i) == find(j)){
31                     vis[j] = 1;
32                 }
33             }
34         }
35         return ans;
36     }
37 };
View Code

find那里可以递归也可以while循环

union那里在函数里找祖先也可以在主函数里找祖先

我这边习惯主函数简洁

posted @ 2022-04-25 10:19  剩下的交给时间就好  阅读(14)  评论(0编辑  收藏  举报