80742 - 同测活动第4场提高组阅读程序3
统计题目(材料题)
1 #include <iostream>
2 using namespace std;
3
4 bool isPrime(int n) {
5 if (n < 2) return false;
6 if (n == 2 || n == 3) return true;
7 if ((n & 1) == 0) return false;
8 for (int i = 3; i * i <= n; i += 2)
9 if (n % i == 0) return false;
10 return true;
11 }
12
13 int main() {
14 int l, r;
15 cin >> l >> r;
16 int cnt = 0;
17
18 for (int i = l; i <= r; i++) {
19 if (isPrime(i)) {
20 int power2 = 1;
21 while (power2 < i) power2 <<= 1;
22 if ((power2 - i) <= 2 || (i - (power2 >> 1)) <= 2)
23 cnt++;
24 }
25 }
26 cout << cnt << endl;
27 return 0;
28 }
||
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