划线的区域根本就不需要！
> my code:
> 
> #include <stdio.h>
> #include <math.h>
> #define sum(x) x*(x+1)/2
> 
> main()
> {
>   int i,n,s;
>   scanf("%d",&s);
>   n=(1+(int)sqrt(-1+8*s))/2;

>   for(i=n;;i++)
~~~~~~~~~~~~~~~~~
>     if(sum(i-1)<s )
~~~~~~~~~~~~~~~~~~~~
>       break;
~~~~~~~~~~~~~~
>  ((sum(i)-s)%2)?((i%2)?printf("%d",i+2):printf("%d",i+1)):printf("%d",i);
>  return 0;         
> }
>