Merkkijono

#include <iostream>
#include <string>

using namespace std;

int main() {
	string str;
	cin >> str;
	bool done = false;
	char lastChar = '\0';
	int i = 0;
	int start = 0;
	int end = 0;
	bool found = false;
	int size = 0;
	while (!done) {
		start = -1;
		end = 0;
		lastChar = '\0';
		found = false;
		size = str.size();
		for (i = 0; i < size; i++) {
			char cur = str.at(i);
			if (cur == lastChar) {
				found = true;
				if (start == -1) {
					start = i - 1;
				}
				end = i;
			} else {
				if (start != -1) {
					end++;
					if (end == size - 1) {
						end = size;
					}
					str.erase(str.begin() + start, str.begin() + end);
					size = str.size();
					start = -1;
				}
				lastChar = cur;
			}
		}
		if (start != -1) {
			str.erase(str.begin() + start, str.begin() + end);
		}
		if (!found) {
			done = true;
		}
	}
	cout << str;
	while (1);
	return 0;
}

Test 1

Verdict: TIME LIMIT EXCEEDED

Test 2

Verdict: TIME LIMIT EXCEEDED

Test 3

Verdict: TIME LIMIT EXCEEDED

Test 4

Verdict: TIME LIMIT EXCEEDED

Test 5

Verdict: TIME LIMIT EXCEEDED

Test 6

Verdict: TIME LIMIT EXCEEDED

Test 7

Verdict: TIME LIMIT EXCEEDED

Test 8

Verdict: TIME LIMIT EXCEEDED

Test 9

Verdict: TIME LIMIT EXCEEDED

Test 10

Verdict: TIME LIMIT EXCEEDED