23 lines
558 B
C++
23 lines
558 B
C++
#include <bits/stdc++.h>
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//https://www.jianshu.com/p/f16d318efe9b
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using namespace std;
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const int N = 1000000;
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int check[N];//元素值为0代表是素数
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int prime[N];
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int main() {
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int cnt = 0;
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for (int i = 2; i < N; i++) {
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//如果是素数
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if (!check[i]) prime[cnt++] = i;
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for (int j = 0; j < cnt && i * prime[j] < N; j++) {
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check[i * prime[j]] = 1;//筛掉
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if (i % prime[j] == 0) break;
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}
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}
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printf("%.2f", (double) clock() / CLOCKS_PER_SEC);
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return 0;
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}
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