Primes Below a Bound

Medium

You get an integer limit. Return how many prime numbers are strictly less than limit. A prime is a number greater than 1 whose only divisors are 1 and itself.

Example 1

limit=20 → 8

There are eight primes below 20: 2, 3, 5, 7, 11, 13, 17, 19.

Example 2

limit=3 → 1

Only 2 is prime and below 3. The bound itself does not count, since the primes must be strictly smaller.

Example 3

limit=1 → 0

Constraints

0 ≤ limit ≤ 5 · 10⁶

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Topics

Array Math Enumeration Number Theory

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Input

limit=20

Expected

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