Looking for good programming challenges?

Use the search below to find our solutions for selected questions!

All posts in Algorithms

Buy and sell a stock k times

Problem statement Write a program to compute the maximum profit that can be made by buying and selling a share times over a given day range. Your program takes and an array of daily stock prices as input. Solution At any given day you can either make a transaction or . . . Read more

Pots of gold

Problem statement Pots of gold game: Two players and . There are pots of gold arranged in a line, each containing some gold coins (the players can see how many coins are there in each gold pot – perfect information). They get alternating turns in which the player can pick . . . Read more

Lego blocks challenge

You have types of lego blocks, of sizes given as , and . Assume that you have an infinite number of blocks of each type. Using these blocks, you want to make a wall of height and width . The wall should not have any holes in it. The wall . . . Read more

Longest Increasing Continuous Subsequence

Problem statement Given an array of numbers, find the longest increasing continuous subsequence. Sample Input 3 4 1 2 3 3 4 5 10 99 100 80 Sample Output 3 4 5 10 99 100 Solution public static int[] longestIncreasingContSubSq(int[] arr) { int subSeqLength = 1; int longest = 1; . . . Read more

Sieve of Eratosthenes in interval

In a previous post I illustrated how we can enumerate all the prime numbers up to a given range using a well-known approach called Sieve of Eratosthenes. But what if we want to enumerate all the prime numbers within a given interval ? Instead of just crossing off multiples of . . . Read more

Implement a ceil() function

In this post I will explain a less intuitive approach of implementing a ceil() function in Java, that is faster than known comparison approaches. A few known facts Fact 1 Dividing two integers and in Java will always floor the result: int a, b; int ans = a/b; // is . . . Read more

Mr. Twotwo challenge

Mr. Twotwo as the name suggests is very fond powers of . Moreover he also has special affinity to number . He is known for carrying quirky experiments on powers of . One day he played a game in his class. He brought some number plates on each of which . . . Read more

Cut the sticks challenge

Problem statement You are given sticks, where the length of each stick is a positive integer. A cut operation is performed on the sticks such that all of them are reduced by the length of the smallest stick. Suppose we have six sticks of the following lengths: 5 4 4 . . . Read more

Find peak in array

Problem statement A peak element is an element that is greater than its neighbors. Given an input array where , find a peak element and return its index. The array may contain multiple peaks, in that case return the index to any one of the peaks is fine. You may . . . Read more