Submission #4030851

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Source Code Expand

#include <iostream>
#include <algorithm>
#include <vector>
#include <map>
#include <set>
#include <string>
#include <cmath>
#include <iomanip>
#include <queue>
#include <unordered_map>
#include <unordered_set>
#include <bitset>
#include <cassert>
#include <cstring>
#include <climits>

using namespace std;

#define FOR(i, a, b) for (int i = (a); i < (b); i++)
#define REP(i, n) FOR(i, 0, n)
#define SORT(c) sort((c).begin(), (c).end())

typedef long long ll;
typedef pair<int, int> P;
typedef vector<int> V;
typedef map<int, int> M;

constexpr ll INF = 1e18;
constexpr ll MOD = 1e9 + 7;
constexpr double PI = 3.14159265358979323846;
constexpr int dx[] = {0, 0, 1, -1};
constexpr int dy[] = {1, -1, 0, 0};

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    int n, a[112345];

    cin >> n;
    REP(i, n)
    cin >> a[i];

    int res = 0;

    bool used[112345] = {false};

    for (int i = 30; i >= 0; i--)
    {
        int cnt = 0;
        int exa = -1;
        REP(j, n)
        {
            if ((a[j] == (1 << i)) && !used[j])
                exa = j;
            if (a[j] & (1 << i))
            {
                cnt++;
                a[j] -= (1 << i);
            }
        }

        if (cnt % 2)
        {
            if (exa == -1)
            {
                cout << -1 << endl;
                return 0;
            }
            else
            {
                used[exa] = true;
                a[exa]--;
                a[exa] += (1 << i);
                res++;
            }
        }
    }

    cout << res << endl;

    return 0;
}

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