257. Binary Tree Paths

Given a binary tree, return all root-to-leaf paths.

Note: A leaf is a node with no children.

Example:

Input:
   1
 /   \
2     3
 \
  5
Output: ["1->2->5", "1->3"]
Explanation: All root-to-leaf paths are: 1->2->5, 1->3

/**
 * Definition for a binary tree node.
 * function TreeNode(val) {
 *     this.val = val;
 *     this.left = this.right = null;
 * }
 */
/**
 * @param {TreeNode} root
 * @return {string[]}
 */
var binaryTreePaths = function(root) {
    if (!root) {
        return [];
    }
    const result = [];
    function traverse(node, path = []) {
        let newPath = [];
        if (node.left) {
            newPath = path.slice(0);
            newPath.push(node.val);
            traverse(node.left, newPath);
        }
        if (node.right) {
            newPath = path.slice(0);
            newPath.push(node.val);
            traverse(node.right, newPath);
        }
        if (!node.left && !node.right) {
            path.push(node.val);
            result.push(path.join('->'));
        }
    }
    traverse(root);
    return result;
};