Tag archives for bottom-up

  1. LeetCode in Swift: Binary Tree Level Order Traversal II

    Problem Statement Given a binary tree, return the bottom-up level order traversal of its nodes’ values. (ie, from left to right, level by level from leaf to root). For example: Given binary tree {3,9,20,#,#,15,7},

    return its bottom-up level order traversal as:

    Original LeetCode problem page My Solution in Swift Continue reading...

  2. LeetCode in Swift: Sort List

    Problem Statement Sort a linked list in O(n log n) time using constant space complexity. Original LeetCode problem page My Solution in Swift I used a bottom-up iterative merge-sort to solve this problem with O(n log n) time efficiency and O(1) space efficiency. Note that, you cannot use traditional recursive merge-sort to tackle this problem; Continue reading...