89分求助

P1217 [USACO1.5] 回文质数 Prime Palindromes

D_M_S_C2310_47 @ 2023-08-30 10:57:50

#include<bits/stdc++.h>
using namespace std;
bool weishu(int n){
    if((n>999&&n<10000)||(n>99999&&n<1000000))return 0;
    return 1;
}
bool zhishu(int n){
    if(n==2)return 1;
    for(int i=2;i<=sqrt(n);i++)
        if(n%i==0)return 0;
    return 1;
}
bool huiwen(int n){
    int a[8],tot=1;
    while(n>0){
        a[tot]=n%10;
        n/=10,tot++;
    }
    for(int i=1;i<=tot/2;i++)
        if(a[i]!=a[tot-i])return 0;
    return 1;
}
int main(){
    int l,r,i;
    cin>>l>>r;
    r=min(9999999,r);
    if(l==2)printf("2\n");
    if(l%2==0)l++;
    for(i=l;i<r;i+=2){
        if(huiwen(i)==0)continue;
        if(zhishu(i)==0)continue;
        if(weishu(i)==0)continue;
        printf("%d\n",i);
    }
    return 0;
}

by BLuemoon_ @ 2023-08-30 11:22:28


by BLuemoon_ @ 2023-08-30 11:22:52


by BLuemoon_ @ 2023-08-30 11:23:13

@违规用户名js$dO^k5 暴力筛肯定会T掉啊


by D_M_S_C2310_47 @ 2023-09-01 11:26:52

@BLuemoon_ 不会


by LZQ_0626 @ 2023-09-03 21:34:10

暴力筛也可以吧


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