All Articles - Hazrat Ali Problem Solving

Apr 19, 2025 • HackerRank

Pangrams

A pangram is a string that contains every letter of the alphabet. Given a sentence determine whether it is a pangram in the English alphabet

Apr 19, 2025 • Codeforces

Jon Snow and his Favourite Number

Jon Snow now has to fight with White Walkers. He has n rangers, each of which has his own strength.

Apr 19, 2025 • Leetcode

Detect Capital

We define the usage of capitals in a word to be right when one of the following cases holds:

Apr 19, 2025 • Codechef

CRED Coins

For each bill you pay using CRED, you earn X CRED coins. At CodeChef store, each bag is worth 100 CRED coins.

Apr 18, 2025 • HackerRank

HackerRank in a String

We say that a string contains the word hackerrank if a of its characters spell the word hackerrank. Remeber that a subsequence maintains the order of characters

Apr 18, 2025 • Codeforces

Timofey and cubes

Young Timofey has a birthday today! He got kit of n cubes as a birthday present from his parents.

Apr 18, 2025 • Codechef

Mahasena

Kattapa, as you all know was one of the greatest warriors of his time

Apr 18, 2025 • Leetcode

Binary Watch

A binary watch has 4 LEDs on the top to represent the hours (0-11), and 6 LEDs on the bottom to represent the minutes (0-59). Each LED represents a zero or one.

Apr 17, 2025 • Codechef

Chef in his Office

Recently Chef joined a new company. In this company, the employees have to work for X

Apr 17, 2025 • Codeforces

Game With Sticks

After winning gold and silver in IOI 2014, Akshat and Malvika want to have some fun. Now they are playing a game on a grid made of n horizontal and m vertical.

Apr 17, 2025 • Leetcode

Longest Palindrome

Given a string s which consists of lowercase or uppercase letters, return the length of the longest palindrome that can be built with those letters.

Apr 16, 2025 • HackerRank

Making Anagrams

We consider two strings to be anagrams of each other if the first string's letters can be rearranged to form the second string.

Apr 16, 2025 • Codeforces

Mahmoud and a Triangle

Mahmoud has n line segments, the i-th of them has length ai. Ehab challenged him to use exactly 3 line segments to form a non-degenerate triangle.

Apr 16, 2025 • Leetcode

Longest Common Prefix

Write a function to find the longest common prefix string amongst an array of strings.

Apr 15, 2025 • Codechef

Janmansh and Assignments

Janmansh has to submit 3 assignments for Chingari before 10 pm and he starts

Apr 15, 2025 • HackerRank

Frog in Maze

Alef the Frog is in an two-dimensional maze represented as a table.

Apr 15, 2025 • Codechef

Subscriptions

A new TV streaming service was recently started in Chefland called the Chef-TV.

Apr 15, 2025 • Leetcode

Repeated String Match

Given two strings a and b, return the minimum number of times you should repeat string a so that string b is a substring of it.

Apr 15, 2025 • Codeforces

Timofey and cubes

Young Timofey has a birthday today! He got kit of n cubes as a birthday present from his parents

Apr 14, 2025 • Codechef

Greater Average

Determine whether the average of A and B is strictly greater than C or not?

Apr 14, 2025 • HackerRank

Organizing Containers of Balls

David has several containers, each with a number of balls in it. He has just enough containers to sort each type of ball he has into its own container.

Apr 14, 2025 • Leetcode

Valid Parentheses

Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

Apr 14, 2025 • Codeforces

Neverending competitions

There are literally dozens of snooker competitions held each year, and team Jinotega

Apr 13, 2025 • Codechef

Valentine is Coming

Valentine's Day is approaching and thus Chef wants to buy some chocolates for someone special.

Apr 13, 2025 • HackerRank

Non-Divisible Subset

Given a set of distinct integers, print the size of a maximal subset of where the sum of any numbers in is not evenly divisible by k.

Apr 13, 2025 • Leetcode

Count and Say

The count-and-say sequence is a sequence of digit strings defined by the recursive formula

Apr 13, 2025 • Codeforces

A Serial Killer

Sherlock is currently trying to catch a serial killer who kills a person each day.

Apr 12, 2025 • HackerRank

Append and Delete

You have two strings of lowercase English letters. You can perform two types of operations on the first string

Apr 12, 2025 • Codeforces

Polycarp and Letters

Polycarp loves lowercase letters and dislikes uppercase ones. Once he got a string s consisting only of lowercase and uppercase Latin letters.

Apr 12, 2025 • Leetcode

Group Anagrams

Given an array of strings strs, group the anagrams together. You can return the answer in any order.

Apr 12, 2025 • Codechef

Reverse The Number

Given an Integer N, write a program to reverse it.

Apr 11, 2025 • HackerRank

Equalize the Array

Given an array of integers, determine the minimum number of elements to delete to leave only elements of equal value.

Apr 11, 2025 • Codechef

Nearest Exit

There are two exits in a bus with 100 seats

Apr 11, 2025 • Codeforces

Anton and Fairy Tale

Anton likes to listen to fairy tales, especially when Danik, Anton's best friend, tells them. Right now Danik tells Anton a fairy tale.

Apr 11, 2025 • Leetcode

Add Binary

Given two binary strings a and b, return their sum as a binary string.

Apr 11, 2025 • HackerRank

Extra Long Factorials

The factorial of the integer , written , is defined as

Apr 10, 2025 • Codeforces

Taymyr is calling you

Comrade Dujikov is busy choosing artists for Timofey's birthday and is recieving calls from Taymyr from Ilia-alpinist.

Apr 10, 2025 • Codechef

Is the Score Consistent

Chef is watching a football match. The current score is A

Apr 10, 2025 • Leetcode

Best Time to Buy and Sell Stock

You are given an array prices where prices[i] is the price of a given stock on the ith day.

Apr 10, 2025 • HackerRank

Jumping on the Clouds: Revisited

A child is playing a cloud hopping game. In this game, there are sequentially numbered clouds that can be thunderheads or cumulus clouds.

Apr 09, 2025 • Codeforces

Petya and Strings

Little Petya loves presents. His mum bought him two strings of the same size for his birthday

Apr 09, 2025 • Leetcode

Reverse Integer

Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range.

Apr 09, 2025 • Codechef

Best of Two

Chef took an examination two times. In the first attempt, he scored XX marks while in the second attempt he scored YY marks

Apr 08, 2025 • HackerRank

Repeated String

There is a string of lowercase English letters that is repeated infinitely many times. Given an integer

Apr 08, 2025 • Codeforces

Soldier and Bananas

A soldier wants to buy w bananas in the shop. He has to pay k dollars for the first banana.

Apr 08, 2025 • Leetcode

554 Brick Wall

There is a rectangular brick wall in front of you with n rows of bricks. The ith row has some number of bricks each of the same height (i.e., one unit)

Apr 08, 2025 • Codechef

Monopoly

There is said to be a monopoly in the market if the profit made by one company is strictly greater than the sum of profits made by all other companies

Apr 08, 2025 • HackerRank

Taum and B'day

Taum is planning to celebrate the birthday of his friend, Diksha. There are two types of gifts that Diksha wants from Taum

Apr 07, 2025 • Codechef

Elections in Chefland

Election season has started in Chefland and the election commission wants to know the count of eligible voters.

Apr 07, 2025 • Leetcode

461 Hamming Distance

The Hamming distance between two integers is the number of positions at which the corresponding bits are different.

Apr 07, 2025 • Codeforces

118A String Task

There are n stones on the table in a row, each of them can be red

Apr 07, 2025 • HackerRank

Jumping on the Clouds

There is a new mobile game that starts with consecutively numbered clouds.

Apr 06, 2025 • HackerRank

Sherlock and Squares

Watson likes to challenge Sherlock's math ability. He will provide a starting and ending value that describe a range of integers.

Apr 06, 2025 • Codeforces

266B Queue at the School

During the break the schoolchildren, boys and girls, formed a queue of n people in the canteen.

Apr 06, 2025 • Leetcode

221 Maximal Square

Given an m x n binary matrix filled with 0's and 1's, find the largest square containing only 1's and return its area.

Apr 05, 2025 • Codeforces

4C Registration system

A new e-mail service "Berlandesk" is going to be opened in Berland in the near future

Apr 05, 2025 • Codechef

Difficulty 571 : Car or Bike

Chef wants to reach home as soon as possible. He has two options.

Apr 05, 2025 • Leetcode

542 Matrix

Given an m x n binary matrix mat, return the distance of the nearest 0 for each cell.

Apr 04, 2025 • Leetcode

204. Count Primes

Given an integer n, return the number of prime numbers that are strictly less than n.

Apr 04, 2025 • HackerRank

Circular Array Rotation

John Watson knows of an operation called a right circular rotation on an array of integers.

Apr 04, 2025 • Codeforces

27A Next Test

«Polygon» is a system which allows to create programming tasks in a simple and professional way.

Apr 03, 2025 • Codeforces

379A New Year Candles

Vasily the Programmer loves romance, so this year he decided to illuminate his room with candles

Apr 03, 2025 • HackerRank

Save the Prisoner

A jail has a number of prisoners and a number of treats to pass out to them

Apr 03, 2025 • Leetcode

207 Course Schedule

There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1

Apr 02, 2025 • Codeforces

478A Initial Bet

There are five people playing a game called "Generosity

Apr 02, 2025 • HackerRank

Viral Advertising

HackerLand Enterprise is adopting a new viral advertising strategy

Apr 02, 2025 • Leetcode

367 Valid Perfect Square

Given a positive integer num, return true if num is a perfect square or false otherwise.

Apr 01, 2025 • HackerRank

The Hurdle Race

A video player plays a game in which the character competes in a hurdle race.

Apr 01, 2025 • HackerRank Math

nCr table

Jim is doing his discrete maths homework which requires him to repeatedly calculate nCr(n choose r) for different values of n.

Apr 01, 2025 • Leetcode

35. Search Insert Position

Given a sorted array of distinct integers and a target value, return the index if the target is found. If not, return the index where it would be if it were.

Apr 01, 2025 • Codeforces

266A Stones on the Table

There are n stones on the table in a row, each of them can be red, green or blue

Mar 31, 2025 • Leetcode

69. Sqrt(x)

Given a non-negative integer x, return the square root of x rounded down to the nearest intege.

Mar 30, 2025 • Codeforces

112A Petya and Strings

Little Petya loves presents. His mum bought him two strings of the same size for his birthday

Mar 30, 2025 • Codeforces

427 Prison Transfer

The prison of your city has n prisoners. As the prison can't accommodate all of them, the city mayor has decided to transfer c of the prisoners to a prison.

Mar 30, 2025 • Leetcode

50. Pow(x, n)

Implement pow(x, n), which calculates x raised to the power n (i.e., xn).

Mar 29, 2025 • Codeforces

1734 Select Three Sticks

You are given n sticks with positive integral length a1,a2

Mar 29, 2025 • Codeforces

2490. Circular Sentence

A sentence is a list of words that are separated by a single space with no leading or trailing spaces

Mar 29, 2025 • HackerRank

Migratory Birds

Given an array of bird sightings where every element represents a bird type id

Mar 28, 2025 • Leetcode

62. Unique Paths

There is a robot on an m x n grid. The robot is initially located at the top-left corner.

Mar 27, 2025 • Leetcode

120. Triangle

Given a triangle array, return the minimum path sum from top to bottom

Mar 26, 2025 • Data Structures & Algorithms

Stack Data Structure

A Stack is a linear data structure that follows a particular order in which the operations are performed. The order may be LIFO(Last In First Out).

Mar 26, 2025 • Leetcode

91. Decode Ways

A message containing letters from A-Z is being encoded to numbers using the following mapping.

Mar 26, 2025 • Codeforces

1742C -Stripes

On an 8×8 grid, some horizontal rows have been painted red, and some vertical columns have been painted blue

Mar 25, 2025 • Leetcode

2. Add Two Numbers

You are given two non-empty linked lists representing two non-negative integers.

Mar 25, 2025 • Codeforces

Swap Game

Alice and Bob are playing a game on an array a of n positive integers

Mar 24, 2025 • HackerRank

Angry Professor

A Discrete Mathematics professor has a class of students. Frustrated with their lack of discipline.

Mar 24, 2025 • Leetcode

794. Valid Tic-Tac-Toe State

Given a Tic-Tac-Toe board as a string array board, return true if and only if it is possible to reach

Mar 23, 2025 • HackerRank

Divisible Sum Paris

Given an array of integers and a positive integer , determine the number of pairs where and + is divisible by .

Mar 23, 2025 • Leetcode

394. Decode String

The encoding rule is: k[encoded_string], where the encoded_string inside the square brackets is being repeated exactly k

Mar 22, 2025 • Leetcode

526. Beautiful Arrangement

Suppose you have n integers labeled 1 through n. A permutation of those n integers.

Mar 21, 2025 • Leetcode

318. Maximum Product of Word Lengths

Given a string array words, return the maximum value of length(word[i]) * length(word[j])

Mar 20, 2025 • Leetcode

239. Sliding Window Maximum

You are given an array of integers nums, there is a sliding window of size k.

Mar 19, 2025 • Data Structures & Algorithms

Binary Tree Data Structure

A Binary Tree Data Structure is a hierarchical data structure in which each node has at most two children.

Mar 19, 2025 • Codeforces

Problem - 239A Two Bags of Potatoes

Valera had two bags of potatoes, the first of these bags contains x (x ≥ 1) potatoes.

Mar 19, 2025 • Leetcode

152. Maximum Product Subarray

Given an integer array nums, find a subarray that has the largest product, and return the product.

Mar 18, 2025 • HackerRank

ACM ICPC Team

There are a number of people who will be attending ACM-ICPC World Finals.

Mar 18, 2025 • Leetcode

581. Shortest Unsorted Continuous Subarray

Given an integer array nums, you need to find one continuous subarray such that if you only sort this subarray in non-decreasing order.

Mar 18, 2025 • Codeforces

Problem - 231A

One day three best friends Petya, Vasya and Tonya decided to form a team and take part in programming contests.

Mar 17, 2025 • ICPC (International Collegiate Programming Contest)

47th ICPC World Final 2023

The 47th ICPC World Finals 2023 (International Collegiate Programming Contest) was a prestigious global programming competition where top university.

Mar 17, 2025 • Hackathon

Favourite Singer

Bob has a playlist of N songs, each song has a singer associated with it (denoted by an integer)

Mar 17, 2025 • Codeforces

Problem - 158B Taxi

After the lessons n groups of schoolchildren went outside and decided to visit Polycarpus to celebrate his birthday. We know that the i-th group consists

Mar 17, 2025 • Data Structures & Algorithms

Big O Notation

The efficiency and accuracy of algorithms have to be analysed to compare them and choose a specific algorithm for certain scenarios.

Mar 17, 2025 • HackerRank Math

Find the Point

Consider two points, and . We consider the inversion or point reflection, , of point across point to be a rotation of point around . Given sets of points

Mar 16, 2025 • HackerRank

Staircase

Its base and height are both equal to . It is drawn using # symbols and spaces. The last line is not preceded by any spaces.

Mar 16, 2025 • Leetcode

Maximize Distance to Closest Person

You are given an array representing a row of seats where seats[i] = 1 represents a person sitting in the ith seat, and seats[i] = 0 represents that the ith.

Mar 16, 2025 • Leetcode

Letter Combinations of a Phone Number Problem

Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. Return the answer in any order.

Mar 16, 2025 • Leetcode

Two Sum Problem

LeetCode Problem 1. Given an array of integers nums and an integer target, return indices of the two numbers such that they add up to target.

Mar 16, 2025 • HackerRank

Since 1800 is leap year as per Julian calendar. Day lies on

the year 1800 was a leap year in the Julian calendar. However, by that time, many countries had already switched to the Gregorian calendar, which did not consid

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