Merkkijono

#include <iostream>
#include <string>
#include <cctype>
#include <algorithm>
 
int main(int argc, char* argv[])
{
	std::string str;
	std::cin >> str;
	int loop = 1;
 
	while(loop)
	{
		loop = 0;
		for(unsigned int i = 0; i < str.length(); i++)
		{
			char current = toupper(str[i]);
 
			int j;
			for(j = 0; toupper(str[i + j]) == current; j++);
			if(j > 1)
			{
				str.erase(i, j);
				loop = 1;
				i = -1;
			}
		}
	}
 
	std::cout << str << std::endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED