[LeetCode] 42. Trapping Rain Water
Given n non-negative integers representing an elevation map where the width of each bar is 1, compute how much water it can trap after raining. Example 1:Input: height = [0,1,0,2,1,0,1,3,2,1,2,1]
[LeetCode] 144. Binary Tree Preorder Traversal
Given the root of a binary tree, return the preorder traversal of its nodes’ values. Example 1:Input: root = [1,null,2,3]Output: [1,2,3] Example 2:Input: root = []Output: [] Example 3:Input:
[Leetcode] 58. Length of Last Word
Given a string s consisting of words and spaces, return the length of the last word in the string. A word is a maximal substring consisting of non-space characters only. Example 1:Input: s = “Hel
[LeetCode] 16. 3Sum Closest
Given an integer array nums of length n and an integer target, find three integers in nums such that the sum is closest to target. Return the sum of the three integers. You may assume that each input
[LeetCode] 143. Reorder List
You are given the head of a singly linked-list. The list can be represented as:L0 → L1 → … → Ln - 1 → Ln Reorder the list to be on the following form:L0 → Ln → L1 → Ln - 1 → L2 → Ln - 2 → …You may not
[LeetCode] 21. Merge Two Sorted Lists
You are given the heads of two sorted linked lists list1 and list2. Merge the two lists into one sorted list. The list should be made by splicing together the nodes of the first two lists. Return the
[LeetCode] 142. Linked List Cycle II
Given the head of a linked list, return the node where the cycle begins. If there is no cycle, return null. There is a cycle in a linked list if there is some node in the list that can be reached agai
[LeetCode] 141. Linked List Cycle
Given head, the head of a linked list, determine if the linked list has a cycle in it. There is a cycle in a linked list if there is some node in the list that can be reached again by continuously fol