easy
1656. Design an Ordered Stream
#Problem There is a stream of n (idKey, value) pairs arriving in an arbitrary order, where idKey is an integer between 1 and n and value is a string. No two pairs have the same id. Design a stream that returns the values in increasing order …
2506. Count Pairs Of Similar Strings
#Problem You are given a 0-indexed string array words. Two strings are similar if they consist of the same characters. For example, "abca" and "cba" are similar since both consist of characters 'a', 'b', and 'c'. However, "abacba" and …
2595. Number of Even and Odd Bits
#Problem You are given a positive integer n. Let even denote the number of even indices in the binary representation of n with value 1. Let odd denote the number of odd indices in the binary representation of n with value 1. Note that bits …
1287. Element Appearing More Than 25% In Sorted Array
#Problem Given an integer array sorted in non-decreasing order, there is exactly one integer in the array that occurs more than 25% of the time, return that integer. …
1299. Replace Elements with Greatest Element on Right Side
#Problem Given an array arr, replace every element in that array with the greatest element among the elements to its right, and replace the last element with -1. After doing so, return the array. …
1742. Maximum Number of Balls in a Box
#Problem You are working in a ball factory where you have n balls numbered from lowLimit up to highLimit inclusive (i.e., n == highLimit - lowLimit + 1), and an infinite number of boxes numbered from 1 to infinity. Your job at this factory …
3174. Clear Digits
#Problem You are given a string s. Your task is to remove all digits by doing this operation repeatedly: Delete the first digit and the closest non-digit character to its left. Return the resulting string after removing all digits. …
26. Remove Duplicates from Sorted Array
#Problem Given an integer array nums sorted in non-decreasing order, remove the duplicates in-place such that each unique element appears only once. The relative order of the elements should be kept the same. Then return the number of …
59. Spiral Matrix II
#Problem Given a positive integer n, generate an n x n matrix filled with elements from 1 to n² in spiral order. https://leetcode.cn/problems/spiral-matrix-ii/ Example 1: case1Input: n = 3 Output: [[1,2,3],[8,9,4],[7,6,5]] Example 2: Input: …
47. Permutations II
#Problem Given a collection of numbers, nums, that might contain duplicates, return all possible unique permutations in any order. https://leetcode.cn/problems/permutations-ii/ Example 1: Input: nums = [1,1,2] Output: json 复制 [[1,1,2], …
46. Permutations
#Problem Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order. A permutation is a rearrangement of all the elements of an array. https://leetcode.cn/problems/permutations/ …
1790. Check if One String Swap Can Make Strings Equal
#Problem You are given two strings s1 and s2 of equal length. A string swap is an operation where you choose two indices in a string (not necessarily different) and swap the characters at these indices. Return true if it is possible to make …
90. Subsets II
#Problem Given an integer array nums that may contain duplicates, return all possible subsets (the power set). A subset of an array is a selection of elements (possibly none) of the array. The solution set must not contain duplicate …
78. Subsets
#Problem Given an integer array nums of unique elements, return all possible subsets (the power set). A subset of an array is a selection of elements (possibly none) of the array. The solution set must not contain duplicate subsets. Return …
1800. Maximum Ascending Subarray Sum
#Problem Given an array of positive integers nums, return the maximum possible sum of an ascending subarray in nums. A subarray is defined as a contiguous sequence of numbers in an array. A subarray [numsl, numsl+1, ..., numsr-1, numsr] is …
922. Sort Array By Parity II
#Problem Given an array of integers nums, half of the integers in nums are odd, and the other half are even. Sort the array so that whenever nums[i] is odd, i is odd, and whenever nums[i] is even, i is even. Return any answer array that …
905. Sort Array By Parity
#Problem Given an integer array nums, move all the even integers at the beginning of the array followed by all the odd integers. Return any array that satisfies this condition. https://leetcode.cn/problems/sort-array-by-parity/ Example 1: …
3105. Longest Strictly Increasing or Strictly Decreasing Subarray
#Problem You are given an array of integers nums. Return the length of the longest subarray of nums which is either strictly increasing or strictly decreasing. A subarray is a contiguous non-empty sequence of elements within an array. An …
680. Valid Palindrome II
#Problem Given a string s, return true if the s can be palindrome after deleting at most one character from it. https://leetcode.cn/problems/valid-palindrome-ii/ Example 1: Input: s = "aba" Output: true Example 2: Input: s = "abca" Output: …
1752. Check if Array Is Sorted and Rotated
#Problem Given an array nums, return true if the array was originally sorted in non-decreasing order, then rotated some number of positions (including zero). Otherwise, return false. There may be duplicates in the original array. Note: An …
598. Range Addition II
#Problem You are given an m x n matrix M initialized with all 0’s and an array of operations ops, where ops[i] = [aᵢ, bᵢ] means M[x][y] should be incremented by one for all 0 <= x < aᵢ and 0 <= y < bᵢ. Count and return the number of maximum …
541. Reverse String II
#Problem Given a string s and an integer k, reverse the first k characters for every 2k characters counting from the start of the string. If there are fewer than k characters left, reverse all of them. If there are less than 2k but greater …
344. Reverse String
#Problem Write a function that reverses a string. The input string is given as an array of characters s. You must do this by modifying the input array in-place with O(1) extra memory. https://leetcode.cn/problems/reverse-string/ Example 1: …
350. Intersection of Two Arrays II
#Problem Given two integer arrays nums1 and nums2, return an array of their intersection. Each element in the result must appear as many times as it shows in both arrays and you may return the result in any order. …
349. Intersection of Two Arrays
#Problem Given two integer arrays nums1 and nums2, return an array of their intersection. Each element in the result must be unique and you may return the result in any order. https://leetcode.cn/problems/intersection-of-two-arrays/ Example …
219. Contains Duplicate II
#Problem Given an integer array nums and an integer k, return true if there are two distinct indices i and j in the array such that nums[i] == nums[j] and abs(i - j) <= k. https://leetcode.cn/problems/contains-duplicate-ii/ Example 1: …
118. Pascal’s Triangle
#Problem Given an integer numRows, return the first numRows of Pascal’s triangle. In Pascal’s triangle, each number is the sum of the two numbers directly above it as shown: https://leetcode.cn/problems/pascals-triangle/ pascalExample 1: …
119. Pascal's Triangle II
#Problem Given an integer rowIndex, return the rowIndexᵗʰ (0-indexed) row of the Pascal’s triangle. In Pascal’s triangle, each number is the sum of the two numbers directly above it as shown: …
2239. Find Closest Number to Zero
#Problem Given an integer array nums of size n, return the number with the value closest to 0 in nums. If there are multiple answers, return the number with the largest value. https://leetcode.cn/problems/find-closest-number-to-zero/ …
3095. Shortest Subarray With OR at Least K I
#Problem You are given an array nums of non-negative integers and an integer k. An array is called special if the bitwise OR of all of its elements is at least k. Return the length of the shortest special non-empty subarray of nums, or …
3065. Minimum Operations to Exceed Threshold Value I
#Problem You are given a 0-indexed integer array nums, and an integer k. In one operation, you can remove one occurrence of the smallest element of nums. Return the minimum number of operations needed so that all elements of the array are …
3270. Find the Key of the Numbers
#Problem You are given three positive integers num1, num2, and num3. The key of num1, num2, and num3 is defined as a four-digit number such that: Initially, if any number has less than four digits, it is padded with leading zeros. The iᵗʰ …