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Problems Contests

Practice coding problems

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Practice coding problems

Data structures and algorithms problems in Python and Java. Read any problem for free; sign in to run and submit your code.

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56 problems

ProblemDifficultyTopicsTime

Count Vowels in a StringFoundational
Easy15 min

Programming Fundamentals

Sum of the First N Natural NumbersFoundationalEasy15 min

Mathematics and Number Theory

Count Occurrences of a CharacterFoundationalEasy15 min

Check Whether a Number Is an Armstrong NumberFoundationalEasy15 min

Mathematics and Number Theory

Count the Positive Divisors of a NumberFoundationalEasy15 min

GCD and Divisibility

Find the Least Common MultipleFoundationalEasy15 min

Programming Fundamentals
GCD and Divisibility

Convert a Non-Negative Integer to BinaryFoundationalEasy15 min

Bit Manipulation

Calculate the Sum of Digits at Even and Odd PositionsFoundationalEasy15 min

Reverse an IntegerEasy15 min

Programming Fundamentals

Calculate Factorial of a NumberEasy15 min

Modular Arithmetic

Count Digits in an IntegerEasy10 min

Programming Fundamentals

Check Whether a Number Is PrimeEasy15 min

Primes and Sieves

Find the Greatest Common DivisorEasy15 min

GCD and Divisibility

Count Set Bits in an IntegerFoundationalEasy10 min

Bit Manipulation

Count Pairs With a Given SumFoundationalMedium25 min

Hash-Based Techniques

Find the Number That Appears OnceFoundationalMedium25 min

Bit Manipulation

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