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Solution: Nth Magical Number

Understand how to determine the nth magical number divisible by either of two given integers by applying binary search combined with the inclusion-exclusion principle. Explore how to calculate the count of divisible numbers up to a value and use the least common multiple to avoid double counting. This lesson guides you through implementing an optimized approach with a clear time and space complexity analysis.

Statement

Given three integers n, a, and b, return the nth magical number.

A magical number is defined as a positive integer that is divisible by either a or b.

As the result may be very large, return it modulo 109+710^9+7.

Constraints:

  • 11 \leq n 109\leq 10^9

  • ...