Problem 2

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

unordered_set<string> se;
string a[2000];

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n, k;
    cin >> n >> k;
    for(int i=0;i<n;i++) {
        cin >> a[i];
        se.insert(a[i]);
    }
    int ans = 0;
    for(int i=0;i<n;i++) {
        for(int j=0;j<n;j++) {
            string tmp = "";
            if(i == j) continue;
            for(int x=0;x<k;x++) {
                if(a[i][x] == a[j][x]) tmp += a[i][x];
                else {
                    int alph = 'S' + 'E' + 'T';
                    char p = alph - a[j][x] - a[i][x];
                    tmp += p;
                }
            }
            if(se.count(tmp)) ans++;
        }
    }
    cout << ans / 6 << endl;
}