Hiitdromes

#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for(int i = a; i < (b); i++)
#define all(x) begin(x), end(x)
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;

const int N = 1e3 + 5;

int n;
char a[N];
int f[N][N];

bool good(char x) {
    return x == 'H' || x == 'I' || x == 'T';
}

int main() {
    cin.tie(0)->sync_with_stdio(0);
    cin.exceptions(cin.failbit);
    cin >>n;
    for (int i = 1; i <= n; i++) {
        cin >> a[i];
    } 
    memset(f, 0x3f, sizeof(f));
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            if (i > j) {
                f[i][j] = 0;
            } 
        }
    }
    for (int ln = 1; ln <= n; ln++) {
        for (int i = 1; i + ln - 1 <= n; i++) {
            int j = i + ln - 1;
            if (ln == 1) {
                f[i][j] = 1 - good(a[i]);
            } else {
                f[i][j] = min(f[i + 1][j], f[i][j - 1]) + 1;
                if (a[i] == a[j]) {
                    if (good(a[i]) && good(a[j])) {
                        f[i][j] = min(f[i][j], f[i + 1][j - 1]);
                    }
                }
                if (good(a[i]) || good(a[j])) {
                    f[i][j] = min(f[i][j], f[i + 1][j - 1] + 1);
                }
            }
        }
    }
    cout << f[1][n] << '\n';
    
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED