HIIT remains

#include <bits/stdc++.h>
#define ll long long

using namespace std;

int main () {
  int t;
  cin>>t;
  for (int i = 0; i < t; i++) {
    string s;
    cin>>s;
    ll h, i1, i2, t;
    h = i1 = i2 = t = 0;
    for (char c : s) {
      if (c == 'H') h++;
      else if (c == 'I') i2 += i1, i1 += h;
      else if (c == 'T') t += i2;
    }
    cout<<t<<endl;
  }
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED