题目:
题解:
class Solution {
public:int countPrimes(int n) {vector<int> primes;vector<int> isPrime(n, 1);for (int i = 2; i < n; ++i) {if (isPrime[i]) {primes.push_back(i);}for (int j = 0; j < primes.size() && i * primes[j] < n; ++j) {isPrime[i * primes[j]] = 0;if (i % primes[j] == 0) {break;}}}return primes.size();}
};