Skip to main content

Binary Tree Paths

Problem statement​

Given the root of a binary tree, return all root-to-leaf paths in any order.

A leaf is a node with no children.

Example 1:

Input: root = [1,2,3,null,5]Output: ["1->2->5","1->3"]

Example 2:

Input: root = [1]Output: ["1"]

Constraints:

  • The number of nodes in the tree is in the range [1, 100].
  • -100 <= Node.val <= 100

My 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} root
 * @return {string[]}
 */
var binaryTreePaths = function(root) {
    const results = []
    
    function dfs(path, node) {
        if (!node) {
            return;
        }
        
        if (!node.left && !node.right) {
            results.push(`${path}${node.val}`)
            return;
        }
        
        dfs(`${path}${node.val}->`, node.left)
        dfs(`${path}${node.val}->`, node.right)
    }
    
    dfs("", root)
    
    return results;
};