leetcode

Given a stream of integers and a window size, calculate the moving average of all integers in the sliding window. Implement the MovingAverage class: MovingAverage(int size) Initializes the object with the size of the window size. double next(int val) Returns the moving average of the last size values of the stream. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Example 1: Input ["MovingAverage", "next", "next", "next", "next"] [[3], [1], [10], [3], [5]] Output [null, 1....

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. Since it is impossible to change the length of the array in some languages, you must instead have the result be placed in the first part of the array nums. More formally, if there are k elements after removing the duplicates, then the first k elements of nums should hold the final result....

Given two non-negative integers num1 and num2 represented as strings, return the product of num1 and num2, also represented as a string. Note: You must not use any built-in BigInteger library or convert the inputs to integer directly. 1 2 3 4 5 6 7 8 9 Example 1: Input: num1 = "2", num2 = "3" Output: "6" Example 2: Input: num1 = "123", num2 = "456" Output: "56088" Constraints:...

Implement the myAtoi(string s) function, which converts a string to a 32-bit signed integer (similar to C/C++’s atoi function). The algorithm for myAtoi(string s) is as follows: Read in and ignore any leading whitespace. Check if the next character (if not already at the end of the string) is ‘-’ or ‘+’. Read this character in if it is either. This determines if the final result is negative or positive respectively....

Given an array of integers nums sorted in non-decreasing order, find the starting and ending position of a given target value. If target is not found in the array, return [-1, -1]. You must write an algorithm with O(log n) runtime complexity. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Example 1: Input: nums = [5,7,7,8,8,10], target = 8 Output: [3,4] Example 2: Input: nums = [5,7,7,8,8,10], target = 6 Output: [-1,-1] Example 3: Input: nums = [], target = 0 Output: [-1,-1] Constraints:...

Given two strings s and t of length N, find the maximum number of possible matching pairs in strings s and t after swapping exactly two characters within s. A swap is switching s[i] and s[j], where s[i] and s[j] denotes the character that is present at the ith and jth index of s, respectively. The matching pairs of the two strings are defined as the number of indices for which s[i] and t[i] are equal....

Pair Sums Given a list of n integers arr[0..(n-1)], determine the number of different pairs of elements within it which sum to k. If an integer appears in the list multiple times, each copy is considered to be different; that is, two pairs are considered different if one pair includes at least one array index which the other doesn’t, even if they include the same values. Signature int numberOfWays(int[] arr, int k) Input n is in the range [1, 100,000]....

Given two integer arrays of equal length target and arr. In one step, you can select any non-empty sub-array of arr and reverse it. You are allowed to make any number of steps. Return True if you can make arr equal to target, or False otherwise. 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 27 28 29 30 31 Example 1: Input: target = [1,2,3,4], arr = [2,4,1,3] Output: true Explanation: You can follow the next steps to convert arr to target: 1- Reverse sub-array [2,4,1], arr becomes [1,4,2,3] 2- Reverse sub-array [4,2], arr becomes [1,2,4,3] 3- Reverse sub-array [4,3], arr becomes [1,2,3,4] There are multiple ways to convert arr to target, this is not the only way to do so....

Given a file and assume that you can only read the file using a given method read4, implement a method read to read n characters. Your method read may be called multiple times. Method read4: The API read4 reads four consecutive characters from file, then writes those characters into the buffer array buf4. The return value is the number of actual characters read. Note that read4() has its own file pointer, much like FILE *fp in C....

Android devices have a special lock screen with a 3 x 3 grid of dots. Users can set an “unlock pattern” by connecting the dots in a specific sequence, forming a series of joined line segments where each segment’s endpoints are two consecutive dots in the sequence. A sequence of k dots is a valid unlock pattern if both of the following are true: All the dots in the sequence are distinct....

Given an array of integers nums which is sorted in ascending order, and an integer target, write a function to search target in nums. If target exists, then return its index. Otherwise, return -1. You must write an algorithm with O(log n) runtime complexity. 1 2 3 4 5 6 7 8 9 10 11 Example 1: Input: nums = [-1,0,3,5,9,12], target = 9 Output: 4 Explanation: 9 exists in nums and its index is 4 Example 2: Input: nums = [-1,0,3,5,9,12], target = 2 Output: -1 Explanation: 2 does not exist in nums so return -1 Constraints:...

You are given an array arr of N integers. For each index i, you are required to determine the number of contiguous subarrays that fulfill the following conditions: The value at index i must be the maximum element in the contiguous subarrays, and These contiguous subarrays must either start from or end on index i. Signature int[] countSubarrays(int[] arr) Input Array arr is a non-empty list of unique integers that range between 1 to 1,000,000,000 Size N is between 1 and 1,000,000 Output An array where each index i contains an integer denoting the maximum number of contiguous subarrays of arr[i]...

You have a pointer at index 0 in an array of size arrLen. At each step, you can move 1 position to the left, 1 position to the right in the array, or stay in the same place (The pointer should not be placed outside the array at any time). Given two integers steps and arrLen, return the number of ways such that your pointer still at index 0 after exactly steps steps....

Given a URL startUrl and an interface HtmlParser, implement a Multi-threaded web crawler to crawl all links that are under the same hostname as startUrl. Return all URLs obtained by your web crawler in any order. Your crawler should: Start from the page: startUrl Call HtmlParser.getUrls(url) to get all URLs from a webpage of a given URL. Do not crawl the same link twice. Explore only the links that are under the same hostname as startUrl....

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. 1 2 3 4 5 6 7 8 9 Example 1: Input: arr = [1,2,2,6,6,6,6,7,10] Output: 6 Example 2: Input: arr = [1,1] Output: 1 Constraints: 1 <= arr.length <= 10^4 0 <= arr[i] <= 10^5 Solution 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 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 class Solution { public int findSpecialInteger2(int[] arr) { int n = arr....