leetcode 省份数量

package 图论;

public class 省份数量 {
    public static void main(String[] args) {

    }
    class Solution {
        static int[] parent;
        public int findCircleNum(int[][] isConnected) {
            init(isConnected.length);
            for(int i = 0 ;i < isConnected.length; i++){
                for(int j = i + 1;j < isConnected.length; j++){
                    if(isConnected[i][j] == 1){
                        join(i,j);
                    }
                }
            }
            int res = 0;
            for(int i = 0;i < isConnected.length;i++){
                if(parent[i] == i){ //判断有几个根 就有几个不连通的省份
                    res++;
                }
            }
            return res;
        }
        static void init(int size){
            parent = new int[size];
            for(int i = 0;i < size;i++){
                parent[i] = i;
            }
        }

        static int find(int x){
            if(x == parent[x]){ return x;}
            else{
                return parent[x] = find(parent[x]);
            }
        }

        static boolean isSame(int x,int y){
            int xx = find(x);
            int yy = find(y);
            return xx == yy;
        }

        static void join(int u,int v){
            u = find(u);
            v = find(v);
            if(u == v){
                return;
            }
            parent[u] = v;
        }

    }
}