136. Single Number Given a non-empty array of integers nums, every element appears twice except for one. Find that single one. You must implement a solution with a linear runtime complexity and use only constant extra space. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Example 1: Input: nums = [2,2,1] Output: 1 Example 2: Input: nums = [4,1,2,1,2] Output: 4 Example 3: Input: nums = [1] Output: 1 Constraints:...

137. Single Number II Given an integer array nums where every element appears three times except for one, which appears exactly once. Find the single element and return it. You must implement a solution with a linear runtime complexity and use only constant extra space. 1 2 3 4 5 6 7 8 9 Example 1: Input: nums = [2,2,3,2] Output: 3 Example 2: Input: nums = [0,1,0,1,0,1,99] Output: 99 Constraints:...

190. Reverse Bits Reverse bits of a given 32 bits unsigned integer. Note: Note that in some languages such as Java, there is no unsigned integer type. In this case, both input and output will be given as a signed integer type. They should not affect your implementation, as the integer’s internal binary representation is the same, whether it is signed or unsigned. In Java, the compiler represents the signed integers using 2’s complement notation....

260. Single Number III Given an integer array nums, in which exactly two elements appear only once and all the other elements appear exactly twice. Find the two elements that appear only once. You can return the answer in any order. You must write an algorithm that runs in linear runtime complexity and uses only constant extra space. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Example 1: Input: nums = [1,2,1,3,2,5] Output: [3,5] Explanation: [5, 3] is also a valid answer....

268. Missing Number Given an array nums containing n distinct numbers in the range [0, n], return the only number in the range that is missing from the array. Follow up: Could you implement a solution using only O(1) extra space complexity and O(n) runtime complexity? 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 Example 1: Input: nums = [3,0,1] Output: 2 Explanation: n = 3 since there are 3 numbers, so all numbers are in the range [0,3]....

389. Find the Difference You are given two strings s and t. String t is generated by random shuffling string s and then add one more letter at a random position. Return the letter that was added to t. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Example 1: Input: s = "abcd", t = "abcde" Output: "e" Explanation: 'e' is the letter that was added....

1013. Partition Array Into Three Parts With Equal Sum Given an array of integers arr, return true if we can partition the array into three non-empty parts with equal sums. Formally, we can partition the array if we can find indexes i + 1 < j with (arr[0] + arr[1] + … + arr[i] == arr[i + 1] + arr[i + 2] + … + arr[j - 1] == arr[j] + arr[j + 1] + … + arr[arr....

243. Shortest Word Distance Given an array of strings wordsDict and two different strings that already exist in the array word1 and word2, return the shortest distance between these two words in the list. 1 2 3 4 5 6 7 8 9 Example 1: Input: wordsDict = ["practice", "makes", "perfect", "coding", "makes"], word1 = "coding", word2 = "practice" Output: 3 Example 2: Input: wordsDict = ["practice", "makes", "perfect", "coding", "makes"], word1 = "makes", word2 = "coding" Output: 1 Constraints:...

244. Shortest Word Distance II Design a data structure that will be initialized with a string array, and then it should answer queries of the shortest distance between two different strings from the array. Implement the WordDistance class: WordDistance(String[] wordsDict) initializes the object with the strings array wordsDict. int shortest(String word1, String word2) returns the shortest distance between word1 and word2 in the array wordsDict. 1 2 3 4 5 6 7 8 9 10 11 12 Example 1: Input ["WordDistance", "shortest", "shortest"] [[["practice", "makes", "perfect", "coding", "makes"]], ["coding", "practice"], ["makes", "coding"]] Output [null, 3, 1] Explanation WordDistance wordDistance = new WordDistance(["practice", "makes", "perfect", "coding", "makes"]); wordDistance....

245. Shortest Word Distance III Given an array of strings wordsDict and two strings that already exist in the array word1 and word2, return the shortest distance between these two words in the list. Note that word1 and word2 may be the same. It is guaranteed that they represent two individual words in the list. 1 2 3 4 5 6 7 8 9 Example 1: Input: wordsDict = ["practice", "makes", "perfect", "coding", "makes"], word1 = "makes", word2 = "coding" Output: 1 Example 2: Input: wordsDict = ["practice", "makes", "perfect", "coding", "makes"], word1 = "makes", word2 = "makes" Output: 3 Constraints:...

191. Number of 1 Bits Write a function that takes an unsigned integer and returns the number of ‘1’ bits it has (also known as the Hamming weight). Note: Note that in some languages, such as Java, there is no unsigned integer type. In this case, the input will be given as a signed integer type. It should not affect your implementation, as the integer’s internal binary representation is the same, whether it is signed or unsigned....

231. Power of Two Given an integer n, return true if it is a power of two. Otherwise, return false. An integer n is a power of two, if there exists an integer x such that n == 2x. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Example 1: Input: n = 1 Output: true Explanation: 20 = 1 Example 2: Input: n = 16 Output: true Explanation: 24 = 16 Example 3: Input: n = 3 Output: false Example 4: Input: n = 4 Output: true Example 5: Input: n = 5 Output: false Constraints:...

835. Image Overlap You are given two images img1 and img2 both of size n x n, represented as binary, square matrices of the same size. (A binary matrix has only 0s and 1s as values.) We translate one image however we choose (sliding it left, right, up, or down any number of units), and place it on top of the other image. After, the overlap of this translation is the number of positions that have a 1 in both images....

131. Palindrome Partitioning Given a string s, partition s such that every substring of the partition is a palindrome. Return all possible palindrome partitioning of s. A palindrome string is a string that reads the same backward as forward. 1 2 3 4 5 6 7 8 9 Example 1: Input: s = "aab" Output: [["a","a","b"],["aa","b"]] Example 2: Input: s = "a" Output: [["a"]] Constraints: 1 <= s.length <= 16 s contains only lowercase English letters....

301. Remove Invalid Parentheses Given a string s that contains parentheses and letters, remove the minimum number of invalid parentheses to make the input string valid. Return all the possible results. You may return the answer in any order. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Example 1: Input: s = "()())()" Output: ["(())()","()()()"] Example 2: Input: s = "(a)())()" Output: ["(a())()","(a)()()"] Example 3: Input: s = ")(" Output: [""] Constraints:...