lrqSB @ 2024-08-21 09:52:13
#include<bits/stdc++.h>
using namespace std;
int main() {
int b=0, c = 0, v = 0, f,m;
int a[10];
int min, max, h=0;
cin >> min >> max;
for (int i = min; i <= max; i++) {
for (int j = 1; j <= sqrt(i); j++) {
if (i % j == 0) {
h++;
}
}
if (i <= 9) {
f = 1;
}
if (i > 9 && i <= 99) {
f = 2;
}
if (i > 99 && i <= 999) {
f = 3;
}
if (i > 999 && i <= 9999) {
f = 4;
}
if (i > 9999 && i <= 99999) {
f = 5;
}
if (i > 99999 && i <= 999999) {
f = 6;
}
if (i > 999999 && i <= 9999999) {
f = 7;
}
if (i > 9999999 && i <= 99999999) {
f = 8;
}
if (i > 99999999 && i <= 999999999) {
f = 9;
}
for(int u=0;u<f;u++){
m=(pow(10,u));
a[u]=(i/m) %(10);
}
for (int k = 1; k <= f; k++) {
if (a[k - 1] == a[f - k]) {
b++;
}
}
if (h == 1 && b == f ) {
cout << i << endl;
}
h=0;
b=0;
}
}by lrqSB @ 2024-08-21 09:55:09
很赖的写法，不是吗，先判断位数，再判断素数和回文数。
by Perry6632 @ 2024-08-21 10:07:30
用筛
by Emil_ @ 2024-08-21 10:08:58
@lion0617
#include<bits/stdc++.h>
using namespace std;
bool huiwen(int n){
bool r=true;
int w[15]={};
int k=1;
while(n>0){
w[k]=n%10;
k++;
n/=10;
}
for(int i=1;i<=k;i++){
if(w[i]!=w[k-i]){
r=false;
}
}
return r;
}
int main(){
std::ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int a,b;
cin>>a>>b;
for(int i=a;i<=b;i++){
if(i%2==0){
i++;
}
if(huiwen(i)==true){
bool f=true;
for(int j=2;j<=sqrt(i);j++){
if(i%j==0)
f=false;
}
if(f)
cout<<i<<endl;
}
}
return 0;
}by lrqSB @ 2024-08-21 10:12:39
@Emil_ 懂了
by Emil_ @ 2024-08-21 10:13:51
@lion0617
qiuguan
by lrqSB @ 2024-08-21 10:14:09
@Emil_,std::ios::sync_with_stdio(0);但这句不懂
by hhztl @ 2024-08-21 10:14:48
@lion0617 快读
by lrqSB @ 2024-08-21 10:15:12
cin.tie(0); cout.tie(0); 包括这句
by hhztl @ 2024-08-21 10:15:41
@lion0617 这两句都是快读
by lrqSB @ 2024-08-21 11:03:35
@Emil_ qiuguan，什是么意思