C语言关于回文数的判断

三重回文是什么意思？
回文转成字符串判断比较容易一些

回文数的判断方法如下，三重回文数是啥意思？

#include<stdio.h>
#include <stdlib.h>
#include <time.h>
int fun1(int n)
{
    int i=0,t=n;
    int j = 0;
    char buf[20]={0};
    while(t>0)
    {
        buf[i]= '0'+ t%10;
        i++;
        t/=10;
    }

    for (j=0;j<i/2;j++)
    {
        if(buf[j] != buf[i-1-j])
            return 0;
    }
    return 1;

}

int fun2(int n)
{
    int d,s=0,t=n;
    while(t>0)
    {
        d = t%10;
        s = s*10 + d;
        t /= 10;
    }
    if(s == n)
        return 1;
    else
        return 0;
}

int main()
{
    int n1,n2,i,t;
    srand((unsigned int)time(0));
    n1 = rand()%50000;
    n2 = rand()%50000;
    if(n1>n2)
    {
        t = n1;
        n1 = n2;
        n2 = t;
    }
    for (i=n1;i<n2;i++)
    {
        if(fun1(i))
            printf("%d ",i);
    }
    printf("\n\n");
    for (i=n1;i<n2;i++)
    {
        if(fun2(i))
            printf("%d ",i);
    }
    printf("\n");
    return 0;
}