572. Subtree of Another Tree

Subtree of Another Tree - LeetCodeLeetCode

time: O(n)

space: O(n)

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @param {TreeNode} subRoot
 * @return {boolean}
 */
var isSubtree = function(root, subRoot) {

    const q = [root];
    while(q.length > 0) {
        const curr = q.shift();

        if (curr === null) continue;
        if (curr.val === subRoot.val) {
            if (validate(curr, subRoot)) return true;
        }

        curr.left !== null && q.push(curr.left);
        curr.right !== null && q.push(curr.right);

    }

    return false;
    
};

function validate(node1, node2) {

    if (node1 === null && node2 === null) return true;
    if (node1 === null || node2 === null) return false;
    
    if (node1.val !== node2.val) return false;

    return validate(node1.left, node2.left) && validate(node1.right, node2.right);
}