HIIT remains

#include <iostream>
#include <string>
#include <vector>
 
int main()
{
	std::ios_base::sync_with_stdio(0);
	std::cin.tie(0);
 
	unsigned int n;
	std::cin >> n;
 
	std::vector<size_t> ongoing;
	ongoing.reserve(100000);
 
	std::vector<size_t> finished;
	finished.reserve(100000);
 
	std::cin.get();
 
	char c;
 
	for (size_t i = 0; i < n; i++) {
	  ongoing.clear();
	  finished.clear();
	  std::cin.get(c);
	  while (c != '\n' && !std::cin.eof()) {
 
	    switch (c) {
	    case 'H':
	      ongoing.push_back(0);
	      break;
	    case 'I':
	      for (auto & elem: ongoing) {
		++elem;
	      }
	      break;
	    case 'T':
	      for (auto & elem: ongoing) {
		if (elem >= 2) {
		  finished.push_back(elem);
		}
	      }
	      break;
	    }
	    std::cin.get(c);
	  }
 
	  size_t sum = 0;
	  for (auto elem: finished) {
	    for (size_t j = 0; j < elem; j++) {
	      sum += j;
	    }
	  }
 
	  std::cout << sum << std::endl;
	}
 
 
	return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: RUNTIME ERROR

Test 4

Verdict: RUNTIME ERROR