Fundamental Problems Tutorials

Write a function that takes in an array of positive integers and returns the maximum sum of non-adjacent elements in the array. If the input array is empty, the function should return 0. Sample input [75, 105, 120, 75, 90, 135] Sample output 330 = 75 + 120 + 135 Solution Time Complexity: O(n) Space…

You’re given a non-empty array of positive integers representing the amounts of time that specific queries take to execute. Only one query can be executed at a time, but the queries can be executed in any order. A query’s waiting time is defined as the amount of time that it must wait before its…

The Fibonacci sequence is defined as follows: the first number of the sequence is 0, the second number is 1, and the nth number is the sum of the (n – 1)th and (n – 2)th numbers. Write a function that takes in an integer n and returns the nth Fibonacci number. I have a […]

Write a function that takes in a non-empty string and that returns a boolean representing whether the string is a palindrome. A palindrome is defined as a string that’s written the same forward and backward. Note that single-character strings are palindromes. Solution Loop through half of the…

Write a function that takes in a sorted array of integers as well as a target integer. The function should use the Binary Search algorithm to determine if the target integer is contained in the array and should return its index if it is, otherwise -1. I have a solution here.

Write a function that takes in an array of integers and returns a sorted version of that array. Use the Quick Sort algorithm to sort the array. I have a solution here.

Write a function that takes in a non-empty array of distinct integers and an integer representing a target sum. The function should find all triplets in the array that sum up to the target sum and return a two-dimensional array of all these triplets. The numbers in each triplet should be ordered in…

Write a function that takes in a non-empty array of distinct integers and an integer representing a target sum. If any two numbers in the input array sum up to the target sum, the function should return them in an array, in any order. If no two numbers sum up to the target sum, the […]

It’s photo day at the local school, and you’re the photographer assigned to take class photos. The class that you’ll be photographing has an even number of students, and all these students are wearing red or blue shirts. In fact, exactly half of the class is wearing red shirts, and the other half…