376-and.cpp

/*
 * And  [1013B]
 * Problem:  https://codeforces.com/problemset/problem/1013/B
 * Verdict:  ACCEPTED        Solved: 2021-04-30
 * Language: C++17 (GCC 7-32)
 * Runtime:  46 ms     Memory: 4100 KB
 * Tags:     greedy
 * Author:   BidoTeima
 * Source:   https://codeforces.com/contest/1013/submission/114681717
 */

#include <bits/stdc++.h>
#pragma GCC optimize("-Ofast")
using namespace std;
// Important functions and defines
/// BidoTeima legacy functions
using ll = long long;
ll mod = (ll)1e9+7;
ll MOD = mod;
int64_t POW(int64_t a, int64_t b)
{
    int64_t res = 1;
    while (b > 0)
    {
        if (b % 2 == 1) res = (res*a);
        a = (a*a);
        b /= 2;
    }
    return res;
}
ll sum_range2d(ll i, ll j, ll k, ll l, vector<vector<ll>>& sum)
{
    return sum[k][l] - sum[k][j - 1] - sum[i - 1][l] + sum[i - 1][j - 1];
}
ll GCDAC(ll a, ll b)
{
    if(b==0)
        return a;

    return GCDAC(b, a%b);
}
ll gcd(ll a, ll b)
{
    if(a<b)swap(a,b);
    return GCDAC(a, b);
}
ll lcm(ll a,ll b)
{
    return (a/gcd(a,b))*b;
}
ll dist(ll X1, ll Y1, ll X2, ll Y2)
{
    return sqrt(POW(X1 - X2, 2) + POW(Y1 - Y2, 2));
}
bool intersect(pair<ll, ll> p1, pair<ll, ll> p2)
{
    ll x1 = p1.first, x2 = p1.second, y1 = p2.first, y2 = p2.second;
    return (x1 >= y1 && x1 <= y2) ||
           (x2 >= y1 && x2 <= y2) ||
           (y1 >= x1 && y1 <= x2) ||
           (y2 >= x1 && y2 <= x2);
}
bool isPrime(ll n)
{
    for (ll i = 2; i * i <= n; i++) if (n % i == 0) return false;
    return true;
}
ll inverse(ll n)
{
    return POW(n%mod,mod-2);
}
bool mul_overflow(ll x, ll y) {
    return (log2(x)+log2(y)) >= 64.0;
}
ll ceili(ll x,ll y){
    return (x + y - 1) / y;
}
/*const ll maxn = 30;
ll C[maxn + 1][maxn + 1];
void bin_coeff()
{
    C[0][0] = 1;
    for (ll n = 1; n <= maxn; ++n) {
        C[n][0] = C[n][n] = 1;
        for (ll k = 1; k < n; ++k)
            C[n][k] = ((C[n - 1][k - 1]) + (C[n - 1][k]));
    }
}*/
/*vector<bool> prime(10000005, true);
void sievePrime(ll n)
{
    prime[1]=false;
    for (int p=2; p*p<=n; p++)
    {
        if (prime[p] == true)
        {
            for (int i=p*p; i<=n; i += p)
                prime[i] = false;
        }
    }
}*/
/// End of BidoTeima legacy functions
#define ALL(x) (x).begin(),(x).end()
#define all(cont) (cont).begin(), (cont).end()
#define rall(cont) (cont).rbegin(), (cont).rend()
#define fast     ios::sync_with_stdio(0);cout.tie(0);cin.tie(0);
#define tc int tt;cin>>tt;while(tt--)
int main() {
    fast
    ll n,x;
    cin>>n>>x;
    vector<ll> a(n),b(n);
    vector<int> freq((int)1e5+5,0);
    vector<vector<int>> pos((int)1e5+5);
    bool yes=0;
    for(int i = 0; i < n; i++)
        cin>>a[i],++freq[a[i]],yes|=(freq[a[i]]>1);
    if(yes){
        cout<<0;
        return 0;
    }
    yes=0;
    for(auto&i:a){
        ll res=i&x;
        if(res==i){
            yes|=(freq[res]>1);
        } else yes|=(freq[res]>0);
    }
    if(yes){
        cout<<1;
        return 0;
    }
    yes=0;
    for(int i = 0; i < n; i++) {
        b[i]=a[i]&x;
        pos[b[i]].push_back(i);
    }
    for(int i = 0; i < n; i++) {
        for(auto&el:pos[a[i]&x]){
            if(el!=i){
                cout<<2;
                return 0;
            }
        }
    }
    cout<<-1;
}