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Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct. Constraints: 1 <= nums.length <= 10^5 10^9 <= nums[i] <= 10^9 Example 1: Input: nums = [1,2,3,1] Output: true Example 2: Input: nums = [1,2,3,4] Output: false
Given a string s, find the first nonrepeating character in it and return its index. If it does not exist, return 1. The string s will only contain lowercase English letters. 1 <= s.length <= 10^5 Example 1: Input: s = "leetcode" Output: 0 Example 2: Input: s = "loveleetcode" Output: 2 Example 3: Inp
Given a sorted array nums, remove the duplicates inplace such that each unique element appears only once. The relative order of the elements should be preserved. Return Value: The function should return the new length of the array after removing duplicates. Constraints: Do not allocate extra space f
Given an integer array nums, find the contiguous subarray (containing at least one number) which has the largest sum and return its sum. Constraints: 1 <= nums.length <= 10^5 10^4 <= nums[i] <= 10^4 Example: Input: nums = [2,1,3,4,1,2,1,5,4] Output: 6 Explanation: The subarray [4,1,2,1] has the larg
Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid. An input string is valid if: Open brackets must be closed by the same type of brackets. Open brackets must be closed in the correct order. Every close bracket has a corresponding
Given a string s, determine if it is a permutation of a palindrome. This means the characters of s can be rearranged to form a palindrome. Caseinsensitive: 'A' is considered the same as 'a'. Ignore nonalphanumeric characters: Spaces, punctuation, etc., should be disregarded. Example: Input: "Tact Co
Given a nonempty array of integers, every element appears twice except for one. Find that single one. Your algorithm should have a linear runtime complexity. Could you implement it without using extra memory? Examples: Input: [2,2,1] Output: 1 Input: [4,1,2,1,2] Output: 4
Given an array of strings strs, group the anagrams together. You can return the answer in any order. An anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once.\n\n Constraints:\n 1 <= strs.length <= 10^4\n 0
Given two strings s and t, determine if t is an anagram of s. An anagram is a word or phrase formed by rearranging the letters of a different word or phrase, typically using all the original letters exactly once. Constraints 1 <= s.length, t.length <= 5 10^4 s and t consist of lowercase English lett