872. Leaf-Similar Trees

Problem

Consider all the leaves of a binary tree, from left to right order, the values of those leaves form a leaf value sequence.

For example, in the given tree above, the leaf value sequence is (6, 7, 4, 9, 8).

Two binary trees are considered leaf-similar if their leaf value sequence is the same.

Return true if and only if the two given trees with head nodes root1 and root2 are leaf-similar.

  Example 1:

Input: root1 = [3,5,1,6,2,9,8,null,null,7,4], root2 = [3,5,1,6,7,4,2,null,null,null,null,null,null,9,8]
Output: true

Example 2:

Input: root1 = [1,2,3], root2 = [1,3,2]
Output: false

  Constraints:

• The number of nodes in each tree will be in the range [1, 200].

• Both of the given trees will have values in the range [0, 200].

Solution

/**
 * 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} root1
 * @param {TreeNode} root2
 * @return {boolean}
 */
var leafSimilar = function(root1, root2) {
    var arr1 = [];
    var arr2 = [];
    getLeafNodes(root1, arr1);
    getLeafNodes(root2, arr2);
    return arr1.length === arr2.length
        && arr1.every((item, index) => item === arr2[index]);
};

var getLeafNodes = function(root, result) {
    if (!root.left && !root.right) result.push(root.val);
    root.left && getLeafNodes(root.left, result);
    root.right && getLeafNodes(root.right, result);
};

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).