Problem Given a positive integer N, find the smallest number of steps it will take to reach 1. There are two kinds of permitted steps: You may decrement N to N - 1. If a * b = N, you may decrement N to the larger of a and b. Examples Example 1: Input: N = 100 Output: 5 Explanation: 100 -> 1 with the following route: `100 -> 10 -> 9 -> 3 -> 2 -> 1`. ...
Problem You are given two integer arrays of equal length target and arr. In one step, you can select any non-empty subarray 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. Examples 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 subarray [2,4,1], arr becomes [1,4,2,3] 2- Reverse subarray [4,2], arr becomes [1,2,4,3] 3- Reverse subarray [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. ...
Problem You are given a 0-indexed array of strings details. Each element of details provides information about a given passenger compressed into a string of length 15. The system is such that: The first ten characters consist of the phone number of passengers. The next character denotes the gender of the person. The following two characters are used to indicate the age of the person. The last two characters determine the seat allotted to that person. Return the number of passengers who are strictly more than 60 years old. ...
Problem Using a function rand7() that returns an integer from 1 to 7 (inclusive) with uniform probability, implement a function rand5() that returns an integer from 1 to 5 (inclusive) Solution Method 1 - Using rejection sampling The idea is to use rand7() to generate numbers from 1 to 7, and map these numbers to values between [1, 5]. We need to ensure that the probabilities remain uniform despite the discrepancy between the range of 7 and 5, and we can use acceptance-rejection method to avoid bias. ...
Problem Given an array of integers nums, sort the array in increasing order based on the frequency of the values. If multiple values have the same frequency, sort them in decreasing order. Return the sorted array. Examples Example 1: Input: nums = [1,1,2,2,2,3] Output: [3,1,1,2,2,2] Explanation: '3' has a frequency of 1, '1' has a frequency of 2, and '2' has a frequency of 3. ...
Problem You are given an array of strings names, and an array heights that consists of distinct positive integers. Both arrays are of length n. For each index i, names[i] and heights[i] denote the name and height of the ith person. Return names sorted in descending order by the people’s heights. Examples Example 1: Input: names = ["Mary","John","Emma"], heights = [180,165,170] Output: ["Mary","Emma","John"] Explanation: Mary is the tallest, followed by Emma and John. ...
Problem Given an m x n matrix of distinct numbers, return all lucky numbers in the matrix in any order. A lucky number is an element of the matrix such that it is the minimum element in its row and maximum in its column. Examples Example 1: $$ matrix = \begin{bmatrix} 3 & 7 & 8 \\ 9 & 11 & 13 \\ \colorbox{green} {15} & 16 & 17 \end{bmatrix} $$ ...
Problem You are given an M by N matrix consisting of booleans that represents a board. Each True boolean represents a wall. Each False boolean represents a tile you can walk on. Given this matrix, a start coordinate, and an end coordinate, return the minimum number of steps required to reach the end coordinate from the start. If there is no possible path, then return null. You can move up, left, down, and right. You cannot move through walls. You cannot wrap around the edges of the board. ...
Problem You run an e-commerce website and want to record the last N order ids in a log. Implement a data structure to accomplish this, with the following API: record(order_id): adds the order_id to the log get_last(i): gets the ith last element from the log. i is guaranteed to be smaller than or equal to N. You should be as efficient with time and space as possible. ...
Problem There are numBottles water bottles that are initially full of water. You can exchange numExchange empty water bottles from the market with one full water bottle. The operation of drinking a full water bottle turns it into an empty bottle. Given the two integers numBottles and numExchange, return the maximum number of water bottles you can drink. Examples Example 1: Input: numBottles = 9, numExchange = 3 Output: 13 Explanation: You can exchange 3 empty bottles to get 1 full water bottle. Number of water bottles you can drink: 9 + 3 + 1 = 13. ...