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20 lines
413 B
20 lines
413 B
#include <bits/stdc++.h>
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using namespace std;
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// 判断一个数是不是质数
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bool isPrime(int n) {
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if (n < 2) return false;
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for (int i = 2; i <= n / i; i++)
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if (n % i == 0) return false;
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return true;
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}
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int main() {
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int a, b;
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cin >> a >> b;
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int cnt = 0;
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for (int i = a; i <= b; i++)
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if (isPrime(i)) cnt++;
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cout << cnt << endl;
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return 0;
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} |