[LeetCode] 224. Basic Calculator
Implement a basic calculator to evaluate a simple expression string. The expression string may contain open ( and closing parentheses ), the plus + or minus sign -, non-negative integers and empty spa
[LeetCode] 981. Time Based Key-Value Store
Design a time-based key-value data structure that can store multiple values for the same key at different time stamps and retrieve the key’s value at a certain timestamp. Implement the TimeMap class:
[LeetCode] 85. Maximal Rectangle
Given a rows x cols binary matrix filled with 0’s and 1’s, find the largest rectangle containing only 1’s and return its area. Example 1:Input: matrix = [ [“1”,”0”,”1”,”0”,”0”], [“1”,”0”,”1
[LeetCode] 119. Pascal's Triangle II
Given an integer rowIndex, return the rowIndexth (0-indexed) row of the Pascal’s triangle. In Pascal’s triangle, each number is the sum of the two numbers directly above it as shown: Example 1:Input:
[LeetCode] 118. Pascal's Triangle
Given an integer numRows, return the first numRows of Pascal’s triangle. In Pascal’s triangle, each number is the sum of the two numbers directly above it as shown: Example 1:Input: numRows = 5Ou
[LeetCode] 402. Remove K Digits
Given string num representing a non-negative integer num, and an integer k, return the smallest possible integer after removing k digits from num. Example 1:Input: num = “1432219”, k = 3Outp
[LeetCode] 987. Vertical Order Traversal of a Binary Tree
Given the root of a binary tree, calculate the vertical order traversal of the binary tree. For each node at position (row, col), its left and right children will be at positions (row + 1, col - 1) an
[LeetCode] 314. Binary Tree Vertical Order Traversal
Given the root of a binary tree, return the vertical order traversal of its nodes’ values. (i.e., from top to bottom, column by column). If two nodes are in the same row and column, the order should b