HIIT remains

// ~/.vim/cpp_template.cpp
#include <bits/stdc++.h>
#include <iostream>
#include <vector>
#include <algorithm>
#include <string>

#define REP(i,a,b) for (int i = a; i < b; i++)

// Type Aliases for 1D and 2D vectors with initialization
#define vi(n, val) vector<int>(n, val) // 1D vector of ints with size n, initialized to val
#define vll(n, val) vector<long long>(n, val) // 1D vector of long longs with size n, initialized to val
#define ll long long
#define vvi(n, m, val) vector<vector<int>>(n, vector<int>(m, val)) // 2D vector of ints (n x m), initialized to val
#define vvll(n, m, val) vector<vector<long long>>(n, vector<long long>(m, val)) // 2D vector of long longs (n x m), initialized to val


using namespace std;

template <typename T>
void pV(const std::vector<T>& vec, const std::string& label = "Vector") {
    std::cout << label << ": [ ";
    for (const auto& elem : vec) {
        std::cout << elem << " ";
    }
    std::cout << "]" << std::endl;
}


using namespace std;


void dfs(int s, vector<bool> *visited, vector<int> (*adj)[]) {
    if ((*visited)[s]) return;
    (*visited)[s] = true;
    // process node s


    for (auto u: (*adj)[s]) {
        dfs(u, visited, adj);
    }
}
/*
vector<int> adj[N];                                                          
vector<bool> visited(N, false);
int u, v;
for(int i = 0; i < M;i++){
    cin >> u >> v;
    u--;
    v--;
    adj[u].push_back(v);
    adj[v].push_back(u);
}
*/



int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    // Your code starts here
    int t;
    cin >> t;
    REP(i, 0, t){
        string s;
        cin >> s;
        int n;
        n = s.size();

        vector<long long> H(n, 0), HI(n, 0), HII(n, 0), HIIT(n, 0);
        REP(i, 0, n){
            if(i > 0){
                H[i] = H[i-1];
            }
            if(s[i] == 'H'){
                H[i]++;
            }
        }
        REP(i, 1, n){
            if(s[i] == 'I'){
                HI[i] = H[i-1] + HI[i-1];
            }else{
                HI[i] = HI[i-1];
            }
        }

        REP(i, 1, n){
            if(s[i] == 'I'){
                HII[i] = HI[i-1] + HII[i-1];
            }else{
                HII[i] = HII[i-1];
            }
        }
        REP(i, 1, n){
            if(s[i] == 'T'){
                HIIT[i] = HII[i-1] + HIIT[i-1];
            }else{
                HIIT[i] = HIIT[i-1];
            }
        }
        cout << HIIT[n-1] << endl;
    }

    
    
    return 0;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED