Minimum Absolute Difference in BST

Description

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/

Solution(javascript)

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @return {number}
 */
const getMinimumDifference = (root) => {
  let min = Infinity
  let previous = null
  const aux = (node) => {
    if (!node) {
      return
    }
    if (node.left) {
      aux(node.left)
    }
    const possibleMin = Math.abs(node.val - previous)
    if ((previous !== null) && (possibleMin < min)) {
      min = possibleMin
    }
    previous = node.val
    if (node.right) {
      aux(node.right)
    }
  }
  aux(root)
  return min
}