Combinatorial - Hard Articles

Count of numbers of length N having prime numbers at odd indices and odd numbers at even indices

Given a number N, the task is to calculate the count of numbers of length N having prime numbers at odd indices and odd numbers… Read More

Prime Number

Combinatorial

DSA

Mathematical

Count of N-bit odd and even integers with K set bits

Given two positive integers N and K, the task is to count the number of even and odd integers consisting of N bits, out of… Read More

factorial

Permutation and Combination

Bit Magic

Combinatorial

DSA

Mathematical

Count of distinct N-size Arrays with elements upto K such that adjacent element pair is either ascending or non-multiples

Given two integers N and K, find the distinct number of ways to create an array of N elements where each element is in the… Read More

combinatorics

sieve

Combinatorial

DSA

Dynamic Programming

Greedy

Mathematical

Maximum times X and Y can be reduced to near 0 using numbers A or B

Given 4 integers X, Y, A, B. In one move either decrease X by A and Y by B or decrease X by B and… Read More

Combinatorial

DSA

Mathematical

Count of N digit numbers which contains all single digit primes

Given a positive integer N, the task is to count the number of N-digit numbers which contain all single digit primes. Examples: Input: N =… Read More

digit-DP

Prime Number

Combinatorial

DSA

Dynamic Programming

Mathematical

Count all prime numbers that can be formed using digits of a given number

Given a string S consisting of N digits, the task is to find the number of distinct Prime Numbers that can be formed using the… Read More

Amazon

HashSet

interview-preparation

number-digits

Prime Number

Backtracking

Combinatorial

DSA

Mathematical

Recursion

Strings

Total count of sorted numbers upto N digits in range [L, R] (Magnificent necklace combinatorics problem)

Given three integers N, L, and R, the task is to print the total count of ways to form a necklace of at most N… Read More

digit-DP

Permutation and Combination

Combinatorial

DSA

Dynamic Programming

Mathematical

Misc

Maximum subarray sum in an array created after repeated concatenation | Set-2

Given an array arr[] consisting of N integers and a positive integer K, the task is to find the largest sum of any contiguous subarray… Read More

subarray

subarray-sum

Arrays

Combinatorial

DSA

Mathematical

Minimum difference possible between two given numbers by rearranging their digits in the same order

Given two N-digit positive integers X and Y, the task is to find the minimum absolute difference between both the integers possible by rearranging the… Read More

number-digits

permutation

Arrays

Combinatorial

Competitive Programming

DSA

Mathematical

Maximize cost of forming a set of words using given set of characters

Given an array arr[] consisting of N strings, an array letter[] consisting of M lowercase characters, and an array score[] such that score[i] is the… Read More

Backtracking

Combinatorial

DSA

Mathematical

Recursion

Strings

Generate all possible combinations of K numbers that sums to N

Given two integers N and K, the task is to find all valid combinations of K numbers that adds up to N based on the… Read More

Permutation and Combination

Backtracking

Combinatorial

DSA

Mathematical

Recursion

Number of co-prime pairs from 1 to N which consists of given two digits

Given an integer N and two integers D1 and D2 ( < 10), the task is to find the number of co-prime pairs less than… Read More

number-digits

permutation

Combinatorial

DSA

Mathematical

Count anagrams having first character as a consonant and no pair of consonants or vowels placed adjacently

Given a string S of length N, the task is to count the number of anagrams of S whose first character is a consonant and… Read More

anagram

combinatorics

vowel-consonant

Combinatorial

DSA

Mathematical

Strings

Count ways to make product of array elements even by replacements

Given an array arr[] consisting of N integers, the task is to count the number of ways to make the product of array elements even… Read More

array-rearrange

Technical Scripter 2020

Arrays

Combinatorial

DSA

Technical Scripter

Largest number not exceeding N that does not contain any of the digits of S

Given a numberic string N (1 ≤ |N| ≤ 105) and another numeric string S (1 ≤ |S| ≤ 105), the task is to find… Read More

number-digits

Combinatorial

DSA

Greedy

Mathematical

Strings

Minimize replacements by integers up to K to make the sum of equidistant array elements from the end equal

Given an array arr[] of even length N and an integer K, the task is to minimize the count of replacing array elements by an… Read More

prefix-sum

Arrays

Combinatorial

Divide and Conquer

DSA

Dynamic Programming

Greedy

Count all possible N-length vowel permutations that can be generated based on the given conditions

Given an integer N, the task is to count the number of N-length strings consisting of lowercase vowels that can be generated based the following… Read More

Permutation and Combination

Combinatorial

DSA

Dynamic Programming

Graph

Mathematical

Recursion

Strings

Count pairs whose product contains single distinct prime factor

Given an array arr[] of size N, the task is to count the number of pairs from the given array whose product contains only a… Read More

combinatorics

number-theory

Prime Number

prime-factor

Algorithms

Arrays

C++ Programs

Combinatorial

Competitive Programming

DSA

Hash

Mathematical

Searching

Count ways to split N! into two distinct co-prime factors

Given an integer N, the task is to find the number of ways N! can be split into two distinct factors A and B such… Read More

Prime Number

prime-factor

sieve

Algorithms

Combinatorial

DSA

Greedy

Mathematical

Generate a combination of minimum coins that sums to a given value

Given an array arr[] of size N representing the available denominations and an integer X. The task is to find any combination of the minimum… Read More

dp-coin-change

Permutation and Combination

Backtracking

C++ Programs

Combinatorial

DSA

Dynamic Programming

Mathematical

Recursion