Math / Number Theory

Math problems lean on number theory, combinatorics, and arithmetic insight — GCDs, primes, modular arithmetic, overflow — rather than a data structure. The win usually comes from a formula or property that replaces a loop.

10 LeetCode problems solved with the Math / Number Theory pattern. Practice them with spaced repetition so the pattern sticks.

• Add BinaryEASY · O(max(m, n))
• Excel Sheet Column TitleEASY · O(log n)
• Factorial Trailing ZeroesMEDIUM · O(log n)
• Greatest Common Divisor of StringsEASY · O(n + m)
• Integer to RomanMEDIUM · O(1)
• Multiply StringsMEDIUM · O(m * n)
• Palindrome NumberEASY · O(log10(x))
• Plus OneEASY · O(n)
• Reverse IntegerMEDIUM · O(log x)
• Roman to IntegerEASY · O(n)