204. Count Primes Medium

1/**
2 * [204] Count Primes
3 *
4 * Given an integer n, return the number of prime numbers that are strictly less than n.
5 *  
6 * Example 1:
7 * 
8 * Input: n = 10
9 * Output: 4
10 * Explanation: There are 4 prime numbers less than 10, they are 2, 3, 5, 7.
11 * 
12 * Example 2:
13 * 
14 * Input: n = 0
15 * Output: 0
16 * 
17 * Example 3:
18 * 
19 * Input: n = 1
20 * Output: 0
21 * 
22 *  
23 * Constraints:
24 * 
25 * 	0 <= n <= 5 * 10^6
26 * 
27 */
28pub struct Solution {}
29
30// problem: https://leetcode.com/problems/count-primes/
31// discuss: https://leetcode.com/problems/count-primes/discuss/?currentPage=1&orderBy=most_votes&query=
32
33// submission codes start here
34
35impl Solution {
36    pub fn count_primes(n: i32) -> i32 {
37        0
38    }
39}
40
41// submission codes end
42
43#[cfg(test)]
44mod tests {
45    use super::*;
46
47    #[test]
48    fn test_204() {
49    }
50}
51