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1. Problem 2352. Equal Row and Column Pairs Given a 0-indexed n x n integer matrix grid, return the number of pairs (ri, cj) such that row ri and column cj are equal. A row and column pair is considered equal if they contain the same elements in the same order (i.e., an equal array). Example 1: Input: grid = [[3,2,1],[1,7,6],[2,7,7]] Output:...

1. Problem 1657. Determine if Two Strings Are Close Two strings are considered close if you can attain one from the other using the following operations: Operation 1: Swap any two existing characters. For example, abcde -> aecdb Operation 2: Transform every occurrence of one existing character into another existing ...

1. Problem 2215. Find the Difference of Two Arrays Given two 0-indexed integer arrays nums1 and nums2, return a list answer of size 2 where: answer[0] is a list of all distinct integers in nums1 which are not present in nums2. answer[1] is a list of all distinct integers in nums2 which are not present in nums1. Note that the integers i...

1. Problem 700. Search in a Binary Search Tree You are given the root of a binary search tree (BST) and an integer val. Find the node in the BST that the node’s value equals val and return the subtree rooted with that node. If such a node does not exist, return null. Example 1: Input: root = [4,2,7,1,3], val = 2 Output: [2,1,3] Example 2: ...

1. Problem 724. Find Pivot Index Given an array of integers nums, calculate the pivot index of this array. The pivot index is the index where the sum of all the numbers strictly to the left of the index is equal to the sum of all the numbers strictly to the index’s right. If the index is on the left edge of the array, then the left sum is 0 ...

1. Problem 1732. Find the Highest Altitude There is a biker going on a road trip. The road trip consists of n + 1 points at different altitudes. The biker starts his trip on point 0 with altitude equal 0. You are given an integer array gain of length n where gain[i] is the net gain in altitude between points i​​​​​​ and i + 1 for all (0 <=...

1. Problem 643. Maximum Average Subarray I You are given an integer array nums consisting of n elements, and an integer k. Find a contiguous subarray whose length is equal to k that has the maximum average value and return this value. Any answer with a calculation error less than 10-5 will be accepted. Example 1: Input: nums = [1,12,-5,-6,50...

1. Problem 693. Binary Number with Alternating Bits Given a positive integer, check whether it has alternating bits: namely, if two adjacent bits will always have different values. Example 1: Input: n = 5 Output: true Explanation: The binary representation of 5 is: 101 Example 2: Input: n = 7 Output: false Explanation: The binary representa...

1. Problem 338. Counting Bits Given an integer n, return an array ans of length n + 1 such that for each i (0 <= i <= n), ans[i] is the number of 1’s in the binary representation of i. Example 1: Input: n = 2 Output: [0,1,1] Explanation: 0 --> 0 1 --> 1 2 --> 10 Example 2: Input: n = 5 Output: [0,1,1,2,1,2] Explanation: 0 --&...

1. Problem 151. Reverse Words in a String Given an input string s, reverse the order of the words. A word is defined as a sequence of non-space characters. The words in s will be separated by at least one space. Return a string of the words in reverse order concatenated by a single space. Note that s may contain leading or trailing spaces o...