ds-algo-study/DS-n-Algos/Trees/tree_order_project/lib/leet_code_105.js

Just experimenting with publishing a package

// View the full problem and run the test cases at:
//  https://leetcode.com/problems/construct-binary-tree-from-preorder-and-inorder-traversal/

const { TreeNode } = require('./tree_node.js');

function buildTree(preorder, inorder) {
	const node = new TreeNode(preorder[0]);
	if (!inorder.length) return null;
	if (inorder.length === 1) return node;

	const arr = split(inorder, node.val);

	node.left = buildTree(preorder.slice(1), arr[0]);
	node.right = buildTree(preorder.slice(1 + arr[0].length), arr[1]);

	return node;
}

function split(arr, val) {
	let left = [];
	let right = [];
	for (let i = 0; i < arr.length; i++) {
		if (arr[i] === val) {
			left = arr.slice(0, i);
			right = arr.slice(i + 1);
			break;
		}
	}

	return [left, right];
}