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Problem: Nth Magical Number

hard
40 min
Explore how to calculate the nth magical number defined by divisibility rules for given integers a and b. Understand problem constraints and learn to implement efficient solutions using modular arithmetic and mathematical reasoning.

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

  • 22 \leq a, b 4×104\leq 4 \times 10^4

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Problem
Ask
Submissions

Problem: Nth Magical Number

hard
40 min
Explore how to calculate the nth magical number defined by divisibility rules for given integers a and b. Understand problem constraints and learn to implement efficient solutions using modular arithmetic and mathematical reasoning.

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

  • 22 \leq a, b 4×104\leq 4 \times 10^4