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30 lines
740 B
30 lines
740 B
#include <bits/stdc++.h>
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using namespace std;
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//欧拉筛
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const int N = 1e5 + 10;
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int primes[N], cnt; // primes[]存储所有素数
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bool st[N]; // st[x]存储x是否被筛掉
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void get_primes(int n) {
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for (int i = 2; i <= n; i++) {
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if (!st[i]) primes[cnt++] = i;
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for (int j = 0; primes[j] * i <= n; j++) {
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st[primes[j] * i] = true;
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if (i % primes[j] == 0) break;
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}
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}
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}
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int n;
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int main() {
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cin >> n;
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get_primes(n);
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for (int i = 4; i <= n; i += 2)
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for (int j = 2; j < i; j++)
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if (!st[j] && !st[i - j]) {
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printf("%d=%d+%d\n", i, j, i - j);
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break;
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}
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return 0;
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} |