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Leetcode - 145. Binary Tree Postorder Traversal

· One min read

https://leetcode.com/problems/binary-tree-postorder-traversal/

Solution 1​

/**
 * 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 {number[]}
 */
var postorderTraversal = function (root) {
  let result = [];
  traversalHelper(root, result);
  return result;
};

const traversalHelper = (root, result) => {
  if (root === null) {
    return;
  }
  result.unshift(root.val);
  traversalHelper(root.right, result);
  traversalHelper(root.left, result);
};