42 lines
1017 B
C++
42 lines
1017 B
C++
#include <bits/stdc++.h>
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using namespace std;
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//判断是不是质数
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bool isPrime(int n) { //最快的方法
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if (n < 2) return false;
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if (n == 2 || n == 3) return true;
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if (n % 6 != 1 && n % 6 != 5) return false;
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for (int i = 5; i <= floor(sqrt(n)); i += 6)
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if (n % i == 0 || n % (i + 2) == 0)
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return false;
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return true;
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}
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int main() {
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int n;
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cin >> n;
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//1、找到所有比当前数小的质数
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int a[100] = {0};
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int k = 0;
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for (int i = 2; i <= n; ++i) {
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if (isPrime(i)) {
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a[k++] = i;
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}
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}
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//2、两两配对，是不是加在一起等于当前数
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bool found = false;
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for (int i = 0; i < k; ++i) {
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for (int j = 1; j <= k; ++j) {
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if (a[i] + a[j] == n) {
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cout << n << "=" << a[i] << "+" << a[j] << endl;
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found = true;
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break;
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}
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}
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if (found) break;
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}
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return 0;
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}
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