530 - Minimum Absolute Difference in BST

530. Minimum Absolute Difference in BST

Problem Statement

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:

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

Example 2:

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

 

Constraints:

• The number of nodes in the tree is in the range [2, 104].
• 0 <= Node.val <= 105

 

Note: This question is the same as 783: https://leetcode.com/problems/minimum-distance-between-bst-nodes/

Solutions

Go

package main

import "math"

// Definition for a binary tree node.
type TreeNode struct {
	Val   int
	Left  *TreeNode
	Right *TreeNode
}

func getMinimumDifference(root *TreeNode) int {
	var (
		minDiff = math.MaxInt
		prev    = -1
	)

	var dfs func(*TreeNode)
	dfs = func(node *TreeNode) {
		if node == nil {
			return
		}

		dfs(node.Left)

		if prev != -1 {
			minDiff = int(math.Min(float64(minDiff), float64(node.Val-prev)))
		}
		prev = node.Val

		dfs(node.Right)
	}

	dfs(root)

	return minDiff
}

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