P12020

回文质数

有没有好人帮我解答一下为啥会超时啊

？ · 发布于 2026-02-09 · 浏览 327 回复 2

include<bits/stdc++.h>

using namespace std; long long x, y, a, b, c, d, e;

int main() {

cin >> x >> y;

for (long long i = x; i <= y; i++) {
    long long  t = i;
    long long  w = 0;
    while (t > 0) {
        w = w * 10 + t % 10;
        t = t / 10;
    }
    if (w != i){
    	continue;
	}
    long long z = 1;
    if (i < 2) {
    z = 1;	
	}
    for (long long k = 2; k * k <= i; k++) {
        if (i % k == 0) {
            z =0;
            break;
        }
    }
    
    if (z){
    	cout << i << endl;
	} 
}

return 0;

}

全部回复 共 2 条

  1. 王治国很勇敢 #1 ·

    大于1000000就没有回文质数了

  2. xhy #2 ·

    include <bits/stdc++.h>

    using namespace std;

    int main() {

    int a, b;
cin >> a >> b;

for (int i = a; i <= b; i++) {

	int n = i;
	int sum = 0;

	while (n != 0) {
		int x = n % 10;
		n /= 10;
		sum *= 10;
		sum += x;
	}

	**if (i > 10000000)
		break;//**这里**

	if (i == sum) {
		bool f = true;

		for (int j = 2; j * j <= i; j++) {

			if (i % j == 0) {
				f = false;
				break;
			}
		}

		if (f) {
			cout << i << endl;
		}
	}
}

return 0;

    }

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