Given a data stream input of non-negative integers a1, a2, …, an, …, summarize the numbers seen so far as a list of disjoint intervals.

Given an unsorted array nums, reorder it such that nums[0] < nums[1] > nums[2] < nums[3]….

Andrew has just made a breakthrough in sociology: he realized how to predict whether two persons will be good friends or not. It turns out that each person has ...

Find all pairs of prime numbers (A, B) such that A<=B and their sum is also a prime number and does not exceed N.

You task is to find minimal natural number N, so that N! contains exactly Q zeroes on the trail in decimal notation. As you know N! = 12…*N. For example, 5! = 1...

Nearly prime number is an integer positive number for which it is possible to find such primes P1 and P2 that given number is equal to P1*P2. There is given a s...

Read integers A and B from input file and write their sum in output file.

The Fibonacci sequence of numbers is known: F1 = 1; F2 = 1; Fn+1 = Fn + Fn-1, for n>1. You have to find S - the sum of the first K Fibonacci numbers.

There is sequence 1, 12, 123, 1234, …, 12345678910, … . Given first N elements of that sequence. You must determine amount of numbers in it that are divisible b...

You are given natural numbers a and b. Find a^b-b^a.