hiho第九十三周

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hiho第九十三周

#include <bits/stdc++.h>
#define maxn 1000010
using namespace std;
int mindiv[maxn] = {0};
int prime[maxn], prime_count = 0;
int main()
{int n;scanf( "%d", &n);for (int i = 2; i <= n; i++) {if (mindiv[i] == 0) {prime[prime_count++] = i;}for (int j = 0; j < prime_count && i * prime[j] <= n; j++) {mindiv[i * prime[j]] = prime[j];if (i % prime[j] == 0) break;}}printf( "%d\n", prime_count);return 0;
}