Submission #1287823

#	Time	Username	Problem	Language	Result	Execution time	Memory
1287823		hynmj	Line Town (CCO23_day1problem3)	C++20	0 / 25	1 ms	572 KiB

Main

#include <bits/stdc++.h>
#define int long long
using namespace std;
const long long N = 2e5 + 5;
int a[N];
const int inf = 1e18;
int dp[N][2][2]; // min operations, i = index, j= a[i] == -1  or else , k= operation pending , till i a is sorted;
void solve()
{
    int n;
    cin >> n;
    for (int i = 0; i < n; i++)
    {
        dp[i][0][0] = inf;
        dp[i][0][1] = inf;
        dp[i][1][0] = inf;
        dp[i][1][1] = inf;
        cin >> a[i];
    }

    if (n == 1)
    {
        cout << 0;
        return;
    }
    if (n == 2)
    {
        if (is_sorted(a, a + n))
        {
            cout << 0;
            return;
        }
        else
        {
            cout << -1;
            return;
        }
    }
    int i = 0;
    while (i < n && a[i] == -1)
        i++;
    int count = 0;
    int ans = 0;
    bool ok = 0;
    for (int i = 0; i <= n; i++)
    {
        if (a[i] == -1)
        {
            count++;
        }
        else
        {
            // cout << i << " " << a[i] << endl;
            // cout << count << endl;/
            if (count % 2 == 1)
            {
                cout << -1;
                ok = 1;
                return;
            }
            ans += count / 2;
            count = 0;
        }
    }
    if (ok)
    {
        ans = 1e18;
    }
    i = n - 1;
    while (i >= 0 && a[i] == 1)
        i++;
    count = 0;
    int ans2 = 0;
    for (int i = 0; i <= n; i++)
    {
        if (a[i] == 1)
        {
            count++;
        }
        else
        {
            if (count % 2 == 1 and ans == 1e18)
            {
                cout << -1;
                return;
            }
            if (count % 2 == 1)
            {
                ans2 = 1e18;
            }
            ans2 += count / 2;
            count = 0;
        }
    }
    cout << min(ans, ans2) << endl;
}

signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);
    int t = 1;
    // cin >> t;
    for (int i = 1; i <= t; i++)
    {
        // cout << "Case #" << i << ':' << ' ';
        solve();
        cout << endl;
    }
    return 0;
}

• Subtask 1: 0 / 3
• Subtask 2: 0 / 3
• Subtask 3: 0 / 3
• Subtask 4: 0 / 4
• Subtask 5: 0 / 4
• Subtask 6: 0 / 3
• Subtask 7: 0 / 2
• Subtask 8: 0 / 3