Difficulty/Hard

Problem Given an integer array nums and an integer k, split nums into k non-empty subarrays such that the largest sum of any subarray is minimized. Return the minimized largest sum of the split. A subarray is a contiguous part of the array. Examples Example 1: Input: nums = [7,2,5,10,8], k = 2 Output: 18 Explanation: There are four ways to split nums into two subarrays. The best way is to split it into [7,2,5] and [10,8], where the largest sum among the two subarrays is only 18. ...

Problem Design and implement a data structure for a Least Frequently Used (LFU) cache. Implement the LFUCache class: LFUCache(int capacity) Initializes the object with the capacity of the data structure. int get(int key) Gets the value of the key if the key exists in the cache. Otherwise, returns -1. void put(int key, int value) Update the value of the key if present, or inserts the key if not already present. When the cache reaches its capacity, it should invalidate and remove the least frequently used key before inserting a new item. For this problem, when there is a tie (i.e., two or more keys with the same frequency), the least recently used key would be invalidated. To determine the least frequently used key, a use counter is maintained for each key in the cache. The key with the smallest use counter is the least frequently used key. ...

String Compression 2 Problem Problem Run-length encoding is a string compression method that works by replacing consecutive identical characters (repeated 2 or more times) with the concatenation of the character and the number marking the count of the characters (length of the run). For example, to compress the string "aabccc" we replace "aa" by "a2" and replace "ccc" by "c3". Thus the compressed string becomes "a2bc3". Notice that in this problem, we are not adding '1' after single characters. ...

Problem Given an input string s and a pattern p, implement regular expression matching with support for '.' and '*' where: '.' Matches any single character. '*' Matches zero or more of the preceding element. The matching should cover the entire input string (not partial). Examples Some examples: isMatch("aa","a") ? false isMatch("aa","a.") ? true isMatch("aaa","ab*") ? false isMatch("aa", ".*") ? true isMatch("aa", "a*") ? true isMatch("ab", ".*") ? true isMatch("aabaa", "a*b.*") ? false ...

Problem Given an input string (s) and a pattern (p), implement wildcard pattern matching with support for '?' and '*' where: '?' Matches any single character. '*' Matches any sequence of characters (including the empty sequence). The matching should cover the entire input string (not partial). Examples Example 1: Input: s = "aa", p = "a" Output: false Explanation: "a" does not match the entire string "aa". ...

Problem Given n cuboids where the dimensions of the ith cuboid is cuboids[i] = [widthi, lengthi, heighti] (0-indexed). Choose a subset of cuboids and place them on each other. You can place cuboid i on cuboid j if widthi <= widthj and lengthi <= lengthj and heighti <= heightj. You can rearrange any cuboid’s dimensions by rotating it to put it on another cuboid. Return the maximum height of the stacked cuboids. ...

Problem Given a string, find the longest palindromic substring in linear time i.e. substring that is also a palindrome. Subsequently, Find all palindromic substrings of a given string We have already seen simple O(n^2) solution here - Longest Palindromic Substring Problem, but now lets look at Manacher’s Algorithm, which help us find the solution in linear time. Manacher’s Algorithm #TODO complete this

Problem Convert a non-negative integer num to its English words representation. Examples Example 1: Input: num = 123 Output: "One Hundred Twenty Three" Example 2: Input: num = 12345 Output: "Twelve Thousand Three Hundred Forty Five" Example 3: ...

Problem There are n different online courses numbered from 1 to n. You are given an array courses where courses[i] = [durationi, lastDayi] indicate that the ith course should be taken continuously for durationi days and must be finished before or on lastDayi. You will start on the 1st day and you cannot take two or more courses simultaneously. Return the maximum number of courses that you can take. ...

Problem Given a string s representing a valid expression, implement a basic calculator to evaluate it, and return the result of the evaluation. Note: You are not allowed to use any built-in function which evaluates strings as mathematical expressions, such as eval(). Examples Example 1: Input: s = "3+2*2" Output: 7 Example 2: Input: s = " 3/2 " Output: 1 ...