Out of curiosity I tried submitting your solution. But I got compilation error. Here is the link to my solution. I think this is because of compiler difference. I tried same code on ideone with compiler as C++11 it worked. Need to look at it why it happened. Regarding 2nd part your code is giving garbage value for that test case or maybe you are missing something. See this

1. I think it's included somewhere in <algorithm>, but do not rely on that — you don't want to write non-portable code.

2. It's a sign of undefined behavior or invalid memory access (like array out of bounds).

You can use only one #include for all necessary algorithms.

#include <bits/stdc++.h>