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1. Problem 394. Decode String Given an encoded string, return its decoded string. The encoding rule is: k[encoded_string], where the encoded_string inside the square brackets is being repeated exactly k times. Note that k is guaranteed to be a positive integer. You may assume that the input string is always valid; there are no extra white sp...

1. Problem 1466. Reorder Routes to Make All Paths Lead to the City Zero There are n cities numbered from 0 to n - 1 and n - 1 roads such that there is only one way to travel between two different cities (this network form a tree). Last year, The ministry of transport decided to orient the roads in one direction because they are too narrow. Ro...

1. Problem 2300. Successful Pairs of Spells and Potions You are given two positive integer arrays spells and potions, of length n and m respectively, where spells[i] represents the strength of the ith spell and potions[j] represents the strength of the jth potion. You are also given an integer success. A spell and potion pair is considered su...

1. Problem 1143. Longest Common Subsequence Given two strings text1 and text2, return the length of their longest common subsequence. If there is no common subsequence, return 0. A subsequence of a string is a new string generated from the original string with some characters (can be none) deleted without changing the relative order of the re...

1. Problem 62. Unique Paths There is a robot on an m x n grid. The robot is initially located at the top-left corner (i.e., grid[0][0]). The robot tries to move to the bottom-right corner (i.e., grid[m - 1][n - 1]). The robot can only move either down or right at any point in time. Given the two integers m and n, return the number of possible...

1. Problem 199. Binary Tree Right Side View Given the root of a binary tree, imagine yourself standing on the right side of it, return the values of the nodes you can see ordered from top to bottom. Example 1: Input: root = [1,2,3,null,5,null,4] Output: [1,3,4] Example 2: Input: root = [1,null,3] Output: [1,3] Example 3: Input: root = [] ...

1. Problem 1926. Nearest Exit from Entrance in Maze You are given an m x n matrix maze (0-indexed) with empty cells (represented as ‘.’) and walls (represented as ‘+’). You are also given the entrance of the maze, where entrance = [entrancerow, entrancecol] denotes the row and column of the cell you are initially standing at. In one step, you...

1. Problem 994. Rotting Oranges You are given an m x n grid where each cell can have one of three values: 0 representing an empty cell, 1 representing a fresh orange, or 2 representing a rotten orange. Every minute, any fresh orange that is 4-directionally adjacent to a rotten orange becomes rotten. Return the minimum number of minu...

1. Problem 1493. Longest Subarray of 1’s After Deleting One Element Given a binary array nums, you should delete one element from it. Return the size of the longest non-empty subarray containing only 1’s in the resulting array. Return 0 if there is no such subarray. Example 1: Input: nums = [1,1,0,1] Output: 3 Explanation: After deleting the...

1. Problem 2336. Smallest Number in Infinite Set You have a set which contains all positive integers [1, 2, 3, 4, 5, …]. Implement the SmallestInfiniteSet class: SmallestInfiniteSet() Initializes the SmallestInfiniteSet object to contain all positive integers. int popSmallest() Removes and returns the smallest integer contained in the infini...