class Solution {
    public class Edge{
        int len;//边长度
        int x;//顶点1
        int y;//顶点2
        public Edge(int len,int x,int y){
            this.len = len;
            this.x = x;
            this.y = y;
        }
    }
    public int minCostConnectPoints(int[][] points) {
          int n = points.length;//顶点个数
          List<Edge> edges = new ArrayList<Edge>();
          UnionFind uf = new UnionFind(n);
          for(int i =0;i<n-1;i++){
              for(int j=i+1;j<n;j++){
                  int[] pointi = points[i];
                  int[] pointj = points[j];
                  int len = Math.abs(pointi[0] - pointj[0]) + Math.abs(pointi[1] - pointj[1]);
                  edges.add(new Edge(len,i,j));
              }
          }
           Collections.sort(edges, new Comparator<Edge>() {
            public int compare(Edge edge1, Edge edge2) {
                return edge1.len - edge2.len;
            }
           });
           int sum = 0;
           int index = 0;
           while(uf.count>1){
               Edge edge= edges.get(index);
               boolean flag = uf.Union(edge.x,edge.y);
               if(flag == true)
                  sum += edge.len;
              index+=1;
           }
           return sum;
    }
    public class UnionFind{
        int[] parent;
        int count;
        public int getCount(){
            return count;
        }
        public UnionFind(int n){
            parent = new int[n];
            count = n;
            for(int i =0;i<n;i++)
              parent[i] = i;
        }
        public int find(int x){
            if(parent[x] != x)
               parent[x] = find(parent[x]);
            return parent[x];
        }
        public boolean Union(int x,int y){
            int rootX = find(x);
            int rootY = find(y);
            if(rootX == rootY)
                return false ;
            parent[rootX] = rootY;
            count -= 1;
            return true; 
        }
    }
}