HIIT Generation

#include <iostream>
#include <string>
#include <stdio.h>
#include <math.h>
#include <vector>
 
using namespace std;
 
struct L {
    L(char c) {
        this->c = c;
    }
    char c;
    L *next = nullptr; 
};
 
int main() {
    L *h = new L('H');
    L *i1 = new L('I');
    h->next = i1;
    L *i2 = new L('I');
    i1->next = i2;
    L *t = new L('T');
    i2->next = t;
    L *begin = h;
    int n;
    cin >> n;
    for (int i = 0; i < n; i++) {
        char c;
        cin >> c;
        L *l = begin;
        while (l) {
            if (l->c == c) {
                l->c = 'H';
                L *next = l->next;
                L *i1 = new L('I');
                l->next = i1;
                L *i2 = new L('I');
                i1->next = i2;
                L *t = new L('T');
                i2->next = t;
                t->next = next;
                l = t;
            }
            l = l->next;
        }
    }
    L *l = begin;
    while (l) {
        cout << l->c;  
        l = l->next;
    }
    cout << endl;
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: TIME LIMIT EXCEEDED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED