《88分》

P1217 [USACO1.5] 回文质数 Prime Palindromes

lijuncheng_1207 @ 2023-07-27 18:07:53

#include <bits/stdc++.h>
using namespace std;
int n,m,cnt;
bool prime(int x){
    for(int i=2;i<=sqrt(x);i++) {
        if(x%i==0)
            return 0;
    }
    return 1;
}
bool flag(int x){
    string s=to_string(x);
    string s1=s;
    reverse(s.begin(),s.end());
    if(s1==s){
        return 1;
    }
    return 0;
}
int main(){
    std::ios::sync_with_stdio(false);
    std::cin.tie(0),cout.tie(0); 
    cin>>n>>m;
    for(int i=n;i<=m;i++) {
        if(flag(i)&&prime(i)){
            cout<<i<<endl;
        }
    }
    return 0;
}

by Konjac_Jelly_6 @ 2023-07-27 18:52:04

还有因为要保证 i 为奇数,所以当 a (你的 n )为偶数时,把它变为奇数,即:

if(n%2==0)  n++;

by Konjac_Jelly_6 @ 2023-07-27 18:52:41

@Lijuncheng1207


by lijuncheng_1207 @ 2023-07-27 18:53:16

@所有人(除zbyzby666以外《我已举报》) 收帖


by aguang666 @ 2023-08-03 14:30:49

你只要比一亿小就行了,if(b>=10000000) b=9999999


by wyc0809 @ 2023-08-23 13:06:46

@zbyzby666 已举报,不谢( ̄_, ̄ )


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