530. Minimum Absolute Difference in BST
Given a binary search tree with non-negative values, find the minimum absolute difference between values of any two nodes.
Example:
Input:
1
\
3
/
2
Output:
1
Explanation:
The minimum absolute difference is 1, which is the difference between 2 and 1 (or between 2 and 3).
Note:
- There are at least two nodes in this BST.
- This question is the same as 783: https://leetcode.com/problems/minimum-distance-between-bst-nodes/
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
TreeNode prev = null;
int minDiff = Integer.MAX_VALUE;
public int getMinimumDifference(TreeNode root) {
if(root == null || (root.left == null && root.right == null)) {
return 0;
}
helper(root);
return minDiff;
}
private void helper(TreeNode root) {
if(root != null) {
helper(root.left);
if(prev != null) {
minDiff = Math.min(minDiff, Math.abs(prev.val - root.val));
}
prev = root;
helper(root.right);
}
}
}