#204
Count Primes
medium · verified · 35.8% accepted · 8,770 likes · top 14%
array · math · enumeration · number theory
Description
Given an integer n, return the number of prime numbers that are strictly less than n.
Example 1:
Input: n = 10
Output: 4
Explanation: There are 4 prime numbers less than 10, they are 2, 3, 5, 7.
Example 2:
Input: n = 0
Output: 0
Example 3:
Input: n = 1
Output: 0
Solution