Submission #3729438

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Source Code Expand

#include<iostream>
#include<vector>
#include<algorithm>
#include<set>
#include<map>
#include<unordered_map>
#include<queue>
#include<iomanip>
#include<math.h>
#include<bitset>
#include<cassert>
#include<random>
#include<time.h>
#include<functional>
using namespace std;
using ll=long long;
using ld=long double;
using P=pair<ll,ll>;
#define MOD 1000000007LL
#define INF 1000000000LL
#define EPS 1e-10
#define FOR(i,n,m) for(ll i=n;i<(ll)m;i++)
#define REP(i,n) FOR(i,0,n)
#define DUMP(a) REP(d,a.size()){cout<<a[d];if(d!=a.size()-1)cout<<" ";else cout<<endl;}
#define ALL(v) v.begin(),v.end()
#define UNIQUE(v)  sort(ALL(v));v.erase(unique(ALL(v)),v.end());
#define pb push_back

/* --------------------------------------- */

int main() {
	cin.tie(0);
	ios::sync_with_stdio(false);
	ll n;
	cin >> n;
	vector<ll> a(n);
	REP(i, n) cin >> a[i];
	ll exor = 0;
	REP(i,n) exor ^= a[i];
	vector<bool> cnt(30, false); // 最下位 1 bit が i
	REP(i, n) {
		bitset<30> bi(a[i]);
		REP(j, 30) if(bi[j]) {
			cnt[j] = true;
			break;
		}
	}
	ll ans = 0;
	bitset<30> bi(exor);
	for(ll i = 29; i >= 0; i--) {
		if(bi[i]) {
			if(!cnt[i]) {
				cout << -1 << endl;
				return 0;
			}
			ans++;
			for(ll j = i; j >= 0; j--) bi[j] = bi[j] ^ 1;
		}
	}
	cout << ans << endl;
	return 0;
}

/* --------------------------------------- */

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