Hello guys ,
In the yesterdays lunch time problem : BFRIEND Problem - CodeChef
Here is my code where i was using unsingned long long int and it gave WA : CodeChef: Practical coding for everyone
And here is the same code which i did long long int which gave AC :
https://www.codechef.com/viewsolution/29204946
As no value becomes negative , why is this giving WA ?
Is it because i did abs() function ??
Someone please help me
Thanks
This is because the result of subtraction of two unsigned numbers is also unsigned number. But you may think that -5 is casted to 5 because the sign bit doesn’t matter, but it doesn’t work that way.
In binary signed int -1 is equivalent to unsigned int 4294967295.
Example code: Akt3F5 - Online C++0x Compiler & Debugging Tool - Ideone.com
Try doing the subtraction 0-1 by hand and you will find out that it all happens due to the carry bit.
0000
-0001
------
1111
------
Hope this helps 
I tried submitting your code with an assertion @line 18 here and it resulted in a SIGABRT, i.e. the assertion evaluated to false. So, there is the chance that y can be less than a or b. If you refer to this, you’ll find out that abs(y - b) and abs(y - a) evaluates to 0, which isn’t what you want. You may handle such operations like this. Hope this helps.