C语言训练-自守数问题

解题思路:首先判断自然数和其平方数同时除10得到的余数是否相同，如果相同，循环将两个数除以10后判断余数是否相同（依次比较高位）。

注意事项:自然数的数据类型用long long。

参考代码:

#include

using namespace std;

int main()

{

         for(long long int i = 0; i <= 200000; i++)

         {

                 long long int num = i * i;     

                 int flag = 1, sumflag = 0;

                 if(i <= 10) // 前11个数比较好判断

                 {

                         if((num % 10) == i || i == num)

                         {

                                 if(i == 0)

                                 {

                                         cout << i;

                                 }

                                 else

                                 {

                                         cout << ' ' << ' ' << i;        //提交要的输出格式

                                 }

                         }

                                  continue;

                 }

                 long long int tempA = i,  tempB = num;

                 while(tempA / 10 != 0)     //由于自然数位数比其平方数位数少，所以用自然数除10作为循环条件，

                                                          //               但是存在问题：这个自然数的最高位需要和其平方数的对应位另外比较

                 {

                         if(tempA % 10 == tempB % 10)

                         {

                                 flag = 0;                    //数的对应位相同的标志

                                 sumflag += flag;     

                         }

                         else

                         {

                                 flag = 1;

                                 break;

                         }

                         tempA = tempA / 10;

                         tempB = tempB / 10;

                 }

                 if(sumflag == 0 && tempA % 10 == tempB % 10)

                 {

                          cout << ' ' << ' ' << i ;

                 }

         }

}