repl.it
@shachopin/

Convert BST to Greater Tree

Java

No description

fork
loading
Files
  • Main.java
  • jdt.ls-java-project
Main.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
class Main {
  public static void main(String[] args) {
    System.out.println("Hello world!");
  }
}

MySolution on lintcode 661. Convert BST to Greater Tree
/**
 * Definition of TreeNode:
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left, right;
 *     public TreeNode(int val) {
 *         this.val = val;
 *         this.left = this.right = null;
 *     }
 * }
 */

public class Solution {
    /**
     * @param root: the root of binary tree
     * @return: the new root
     */
     
    int sum = 0;
    public TreeNode convertBST(TreeNode root) {
        // write your code here
        dfs(root);
        return root;
        
    }
    
    private void dfs(TreeNode cur) {
        if (cur == null) {
            return;
        }
        //依赖右中左的顺序
        dfs(cur.right);
        sum += cur.val;
        cur.val = sum;
        dfs(cur.left);
    }
}

=============================================
official solution:

// version: 高频题班
public class Solution {
    /**
     * @param root the root of binary tree
     * @return the new root
     */
    int sum = 0;

    void dfs(TreeNode cur) {
        if (cur == null) {
            return;
        }
        dfs(cur.right);
        sum += cur.val;
        cur.val = sum;
        dfs(cur.left);
    }

    public TreeNode convertBST(TreeNode root) {
        // Write your code here
        dfs(root);
        return root;
    }
}