出处：http://www.dewen.org/q/620

#include 
     
      int judge(int num){  int min = 1;  if(num < 0)  {    return 0;  }  else if(num == 0 || num == 1)  {    return 1;  }  else  {    int current = 2;    while(1)    {      if(current * current < num)      {    min = current;    current = min * 2;      }      else if(current * current == num)      {    return 1;      }      else if(current > min + 1)      {    current = ((min+current)) / 2;      }      else      {    return 0;      }      printf("%d", current);    }  }}int main(){  printf("%d", judge(8));}