Problem Given an array of positive integers nums and a positive integer target, return the minimal length of a subarray whose sum is greater than or equal to target. If there is no such subarray, return 0 instead. OR Given an array of positive integers a and a positive number K, find the length of the smallest contiguous subarray whose sum is greater than or equal to K. Return 0 if no such subarray exists. ...
Problem Given an m x n 2D binary grid grid which represents a map of '1's (land) and '0's (water), return the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water. Examples Example 1: Input: grid = [ ["1","1","1","1","0"], ["1","1","0","1","0"], ["1","1","0","0","0"], ["0","0","0","0","0"] ] Output: 1 ...
Word Frequency From File Problem Write a bash script to calculate the frequency of each word in a text file words.txt. For simplicity sake, you may assume: words.txt contains only lowercase characters and space ' ' characters. Each word must consist of lowercase characters only. Words are separated by one or more whitespace characters. Examples Example: Assume that words.txt has the following content: ...
Problem Given the head of a singly linked list, sort the list using insertion sort, and return the sorted list’s head. The steps of the insertion sort algorithm: Insertion sort iterates, consuming one input element each repetition and growing a sorted output list. At each iteration, insertion sort removes one element from the input data, finds the location it belongs within the sorted list and inserts it there. It repeats until no input elements remain. The following is a graphical example of the insertion sort algorithm. ...
Problem You are given the head of a singly linked-list. The list can be represented as: $$ L_0 → L_1 → … → L_{n - 1} → L_n $$ Reorder the list to be on the following form:: $$ L_0 → L_n → L1 → L_{n - 1} → L2 → L_{n - 2} → … $$ Examples Example 1: --- title: Input List --- graph LR A1[1] --> B2[2] --> C3[3] --> D4[4] ...
Problem Given a string s and a dictionary of words dict, determine if s can be segmented into a space-separated sequence of one or more dictionary words. Examples Example 1: Input: s = "leetcode", wordDict = ["leet","code"] Output: true Explanation: Return true because "leetcode" can be segmented as "leet code". Example 2: ...
Problem Given a binary tree and a sum, find all root-to-leaf paths where each path’s sum equals the given sum. Examples Example 1: graph TD; A[5] --> B[4] & C[8] B --> D[11] & E[null] C --> F[13] & G[4] D --> H[7] & I[2] G --> L[5] & M[1] style A fill:#f9f style B fill:#f9f style C fill:#f9f style D fill:#f9f style I fill:#f9f style G fill:#f9f style L fill:#f9f ...
Problem A message containing letters from A-Z can be encoded into numbers using the following mapping: 'A' -> 1 'B' -> 2 ... 'Z' -> 26 To decode an encoded message, all the digits must be grouped then mapped back into letters using the reverse of the mapping above (there may be multiple ways). For example, "11106" can be mapped into: ...
Problem Given an integer array nums that may contain duplicates, return all possible subsets (the power set). The solution set must not contain duplicate subsets. Return the solution in any order. Examples Example 1: Input: nums = [1,2,2] Output: [ [],[1],[1,2],[1,2,2],[2],[2,2] ] Example 2: Input: nums = [0] Output: [ [],[0] ] ...
Recover Binary Search Tree Problem Problem You are given the root of a binary search tree (BST), where the values of exactly two nodes of the tree were swapped by mistake. Recover the tree without changing its structure. Note: A solution using O(n) space is pretty straight forward. Could you devise a constant space solution? Example Example 1: Input: *1 / *3 \ 2 Output: *3 / *1 \ 2 ...