Description
Submission
class Solution { public: int countPrimes(int n) { if(n < 2) return 0; vector<bool> bucket(n, true); bucket[0] = bucket[1] = false; bucket[2] = true; for(int i = 2; i < n; ++i) { for(int j = 2; j * i < n; ++j) { bucket[j*i] = false; } } int count = 0; for(int i = 0; i < n; ++i) { if(bucket[i]) count++; } return count; } };