There is 64 mb ML in 100083A - Предок. My solusion got with 100 mb, but other people's solutions got AC with 200 mb. How to fix this problem?

GNU G++ 5.1.0 doesn't compile next code:

#include <vector>

using namespace std;

vector <pair <int, int>> a(0);

int main()
{
	return 0;
}

But succeыsfully compile this code:

#include <vector>

using namespace std;

#define pii pair <int, int>

vector <pii> a(0);

int main()
{
	return 0;
}

Why the second code compile without space (" ") after "pii"?

My submission 21624050 got AC, but i tryed this test:

10 2 
1 1 1 0 0 0 0 1 2 2 
1 2

My program's answer is 8, but true answer is 9.

Sending the code, but displays an error on test 1. When run the code in the compiler, everything works as expected. http://codeforces.me/contest/234/submission/20929079

The problem was solved, thanks for help!