binaryTreePaths.js

// 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[]}
 */
const binaryTreePaths = (root) => {
  let res = []
  const pathLoger = (node, prePath = '') => {
    if (!node) return
    let curPath = prePath ? `${prePath}->${node.val}` : `${node.val}` // make it a string
    if (!node.left && !node.right) {
      res.push(curPath)
    }
    pathLoger(node.left, curPath)
    pathLoger(node.right, curPath)
  }
  pathLoger(root)
  return res
}