SPOJ Kompiæi

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

const int OO = 1e9;
const double EPS = 1e-9;

ll cnt[1 << 15];
bool found[10];
ll ans = 0;

void add(int i = 0, int sum = 0) {
    if(i == 10) {
        if(sum != 0) {
            cnt[sum]++;
            //cout << "adding to " << sum << "\n";
        }

    }
    else {
        add(i+1,sum);
        if(found[i])
            add(i+1,sum + (1 << i));
    }
}

void solve(int i = 0, int sum = 0, int taken = 0) {
    if(i == 10) {
        ll curr = (cnt[sum]*(cnt[sum]-1))/2;
        ans += (taken%2 ? 1:-1)*curr;
    }
    else {
        solve(i+1,sum,taken);
        solve(i+1,sum + (1 << i), taken+1);
    }
}

int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    cout.tie(NULL);
    int n;
    cin >> n;
    for(int i = 0; i < n; i++) {
        string s;
        cin >> s;
        for(int k = 0; k < s.size(); k++) {
            found[s[k]-'0'] = 1;
        }
        add();
        for(int i = 0; i < 10; i++) {
            found[i] = 0;
        }
    }
    solve();
    cout << ans << "\n";
    return 0;
}