### vagi's blog

By vagi, history, 2 years ago,

This is about yesterday's Div2 contest Problem B. For reference, here's my code which got RE on system test 7. Finally, I fixed my code and got AC. Read the blunder I made. I hope you people handle it elegantly the next time you encounter this. Pay attention to the last part of the code which includes the two for loops.

Wrong code

The problem here is while outputting the answer, I write the loop's end condition as i < o.size()-1 and i < e.size()-1 . Now, size() returns an unsigned int (In this case, an unsigned 0) and when I subtract 1 from it, like this i < e.size()-1, I get a huge number instead of -1 which I expected I'd get. The loop runs for quite a long time instead of never running at all.

Now, to fix this there are 3 ways you can do so.

1. Typecast the returned value into int like this (int)(e.size()-1).
2. Store this returned value from size method into a variable like this int sz = e.size().
3. As HideBehind mentioned, the simplest way is to write it as i+1 < e.size().

Here's my working code showing both the methods.

Got AC with it

I felt like a dumbo after RE on system tests, fixed it, and then thought to inform you all guys (my first blog).

PS: Making a mistake like this deals some serious damage on ratings XD