/**

* 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} p

* @param {TreeNode} q

* @return {boolean}

*/

var isSameTree = function (p, q) {

// If p and q is null, return true

if (!p && !q) return true;

// Compare root and length between p and q

if (!p || !q || p.val !== q.val) return false;

// Execute recursive function to search each tree

return isSameTree(p.left, q.left) && isSameTree(p.right, q.right);

};

// TC: O(n)

// SC: O(n)