Code Challenges

Get better at coding with practice problems.

Coding Challenges

Select a problem, write code, run test cases, and submit your solution.

Recursion Backtracking Combinatorics

Intermediate

Implement the `restoreIpAddressesCount` method that counts valid IP addresses that can be restored from the digits.

Recursion Backtracking Combinatorics

Proficient

Implement the `palindromePartitionCount` method that counts palindrome partitions possible for the text.

Recursion Backtracking Combinatorics

Intermediate

Implement the `letterCombinationsPhoneCount` method that counts letter combinations generated from phone digits.

Recursion Backtracking Combinatorics

Intermediate

Implement the `sudokuValidPlacementCount` method that counts how many filled Sudoku cells are validly placed.

Recursion Backtracking Combinatorics

Guru

Implement the `nQueensSolutionCount` method that counts valid ways to place n queens on the board.

Recursion Backtracking Combinatorics

Intermediate

Implement the `wordSearchGridExists` method that checks whether a word can be formed in the grid by adjacent cells.

Recursion Backtracking Combinatorics

Learner

Implement the `subsetsCountDistinct` method that counts distinct subsets that can be formed from the values.

Recursion Backtracking Combinatorics

Intermediate

Implement the `permutationsCountDistinct` method that counts distinct permutations of the given values.

Recursion Backtracking Combinatorics

Intermediate

Implement the `combinationSumCount` method that counts combinations that can sum to the target.

Recursion Backtracking Combinatorics

Intermediate

Implement the `generateParenthesesCountImportant` method that counts valid parentheses combinations for n pairs.

Math Number Theory Combinatorics

Proficient

Implement the `countWaysToReachSumWithDice` method that counts dice roll combinations that produce the target sum.

Math Number Theory Combinatorics

Intermediate

Implement the `integerBreakMaximumProduct` method that finds the maximum product after splitting an integer into at least two parts.

Math Number Theory Combinatorics

Learner

Implement the `excelColumnNumber` method that converts an Excel column title into its column number.

Math Number Theory Combinatorics

Intermediate

Implement the `countTrailingZerosFactorial` method that counts trailing zeroes in the factorial of n.

Math Number Theory Combinatorics

Learner

Implement the `isUglyNumber` method that checks whether the number has only 2, 3, and 5 as prime factors.

Math Number Theory Combinatorics

Intermediate

Implement the `lcmArrayValues` method that returns the least common multiple of all array values.

Math Number Theory Combinatorics

Learner

Implement the `gcdArrayValues` method that returns the greatest common divisor of all array values.

Math Number Theory Combinatorics

Intermediate

Implement the `sievePrimeCount` method that counts prime numbers up to n using sieve-style marking.

Math Number Theory Combinatorics

Intermediate

Implement the `powIntegerFast` method that calculates an integer power efficiently using fast exponentiation.