# Algorithm to find Minimum Distance Between BST (binary search tree) Nodes

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

**Example :**

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

**Output:** 1

**Explanation:**

Note that root is a TreeNode object, not an array.

The given tree [4,2,6,1,3,null,null] is represented by the following diagram:

4

/ \

2 6

/ \

1 3

while the minimum difference in this tree is 1, it occurs between node 1 and node 2, also between node 3 and node 2.

**Note:**

- The size of the BST will be between 2 and 100.
- The BST is always valid, each node’s value is an integer, and each node’s value is different.

Anonymous Answered question

- Traverse the tree using tree traversal algorithm for e.g. inorder
- Push all the traversed nodes in an array.
- Sort the array
- Find the minimum difference between array elements by looping through

Javascript code below:-

/** * Definition for a binary tree node. * function TreeNode(val) { * this.val = val; * this.left = this.right = null; * } */ /** * @param {TreeNode} root * @return {number} */ var minDiffInBST = function(root) { var arr = []; inorder(root, arr); arr.sort((a,b)=>a-b); var minDiff = Number.MAX_SAFE_INTEGER; var result = []; var map = {}; for (var i = 0; i < arr.length; i++) { if (typeof map[arr[i]] === 'undefined') { map[arr[i]] = arr[i]; } if (i < arr.length - 1 && Math.abs(arr[i+1] - arr[i]) < minDiff) { minDiff = arr[i+1] - arr[i]; } } return minDiff; }; var inorder = function(root, arr) { if (root) { inorder(root.left, arr); arr.push(root.val); inorder(root.right, arr); } }

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