{leetcode}/problems/count-primes/[LeetCode - Count Primes^]
如何实现一个高效的筛选法？
Count the number of prime numbers less than a non-negative number, n.
Example:
Input: 10 Output: 4 Explanation: There are 4 prime numbers less than 10, they are 2, 3, 5, 7.
link:{sourcedir}/_0204_CountPrimes.java[role=include]