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Problem

Given the root of a Binary Search Tree (BST), return the minimum absolute difference between the values of any two different nodes in the tree.

Example 1:

img

Input: root = [4,2,6,1,3]
Output: 1

Example 2:

img

Input: root = [1,0,48,null,null,12,49]
Output: 1

Constraints:

  • The number of nodes in the tree is in the range [2, 10^4].
  • 0 <= Node.val <= 10^5

Note: This question is the same as 783

Code

重复题目 783

class Solution {
    Integer prev = null;
    int diff = Integer.MAX_VALUE;
    
    public int getMinimumDifference(TreeNode root) {
        helper(root); 
        return diff;
    }
    
    private void helper(TreeNode root){
        if(root == null) return;
        
        helper(root.left);
        
        if(prev == null){
            prev = root.val;
        } else {
            diff = Math.min(diff, root.val - prev);
            prev = root.val;
        }
        
        helper(root.right);
    }
}