# Finding minimum absolute difference within a Binary Search Tree in JavaScript

We are required to write a JavaScript function that takes in the root of a BST that holds some numerical data like this −

1
\
3
/
2

The function should return the minimum absolute difference between any two nodes of the tree.

For example −

For the above tree, the output should be −

const output = 1;

because |1 - 2| = |3 - 2| = 1

## Example

The code for this will be −

Live Demo

class Node{
constructor(data) {
this.data = data;
this.left = null;
this.right = null;
};
};
class BinarySearchTree{
constructor(){
// root of a binary seach tree
this.root = null;
}
insert(data){
var newNode = new Node(data);
if(this.root === null){
this.root = newNode;
}else{
this.insertNode(this.root, newNode);
};
};
insertNode(node, newNode){
if(newNode.data < node.data){
if(node.left === null){
node.left = newNode;
}else{
this.insertNode(node.left, newNode);
};
} else {
if(node.right === null){
node.right = newNode;
}else{
this.insertNode(node.right,newNode);
};
};
};
};
const BST = new BinarySearchTree();
BST.insert(1);
BST.insert(3);
BST.insert(2);
const getMinimumDifference = function(root) {
const nodes = [];
const dfs = (root) => {
if(root) {
dfs(root.left);
nodes.push(root.data);
dfs(root.right);
};
};
dfs(root);
let result = nodes[1] - nodes[0];
for(let i = 1; i < nodes.length - 1; i++) {
result = Math.min(result, nodes[i + 1] - nodes[i]);
};
return result;
};
console.log(getMinimumDifference(BST.root));

## Output

And the output in the console will be −

1

Updated on: 03-Mar-2021

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