提出 #73993221

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ソースコード 拡げる

/*Sin_qwq's code
We can be heros , just for one day .*/
#include <bits/stdc++.h>
#define LD long double
#define i7 __int128
#define re return
#define con continue
#define ci const int
#define all(x) x.begin(), x.end()
#define All(x) x.begin() + 1, x.end()
using namespace std;
typedef long long i64;
template <class T>
inline bool ckmin(T &a, T b) { re b < a ? a = b, 1 : 0; }
template <class T>
inline bool ckmax(T &a, T b) { re a < b ? a = b, 1 : 0; }

int work()
{
    int N, K;
    cin >> N >> K;
    vector<int> A(N + 1);
    for (int i = 1; i <= N; i++)
        cin >> A[i];
    if (K > N)
    {
        for (int i = 1; i <= N; i++)
            if (A[i] == 1)
                return -1;
        return 0;
    }
    int M = N - K + 1;
    vector<int> end(N + K + 2, 0);
    int cur = 0;
    int ans = 0;
    for (int i = 1; i <= N; i++)
    {
        cur ^= end[i];
        int state = A[i] ^ cur;
        if (state == 1)
        {
            if (i > M)
                return -1;
            ans++;
            cur ^= 1;
            end[i + K] ^= 1;
        }
    }
    return ans;
}

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int T = 1;
    // cin>>T;
    while (T--)
    {
        cout << work() << "\n";
    }
    re 0;
}
/*
 */

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