1 public class Solution { 2     private int[] parent; 3     public int countComponents(int n, int[][] edges) { 4         if (edges.length == 0) { 5             return n; 6         } 7         parent = new int[n]; 8         for (int i = 0; i < n; i++) { 9             parent[i] = i;10         }11         12         for (int i = 0; i < edges.length; i++) {13             int aIndex = findParent(edges[i][0]);14             int bIndex = findParent(edges[i][1]);15             16             if (aIndex > bIndex) {17                 parent[aIndex] = bIndex;18             } else if (bIndex > aIndex) {19                 parent[bIndex] = aIndex;20             }21         }22         23         int result = 0;24         for (int i = 0; i < n; i++) {25             if (parent[i] == i) {26                 result++;27             }28         } 29         return result;30     }31     32     private int findParent(int x) {33         while (x != parent[x]) {34             parent[x] = parent[parent[x]];35             x = parent[x];36         }37         return x;38     }39 }