Submission #934609

#	Time	Username	Problem	Language	Result	Execution time	Memory
934609		borisAngelov	Watching (JOI13_watching)	C++17	100 / 100	495 ms	16368 KiB

watching

#include <bits/stdc++.h>

using namespace std;

const int maxn = 2005;
const int inf = 1e9;

int n, p, q;

int a[maxn];

int findPos(int pos, int delta)
{
    int l = 1;
    int r = pos;

    while (l <= r)
    {
        int mid = (l + r) / 2;

        if (a[pos] - a[mid] <= delta)
        {
            r = mid - 1;
        }
        else
        {
            l = mid + 1;
        }
    }

    return l;
}

int prvSmall[maxn];
int prvBig[maxn];

int dp[maxn][maxn];

bool check(int w)
{
    for (int i = 1; i <= n; ++i)
    {
        prvSmall[i] = findPos(i, w - 1);
        prvBig[i] = findPos(i, 2 * w - 1);
    }

    for (int pos = 1; pos <= n; ++pos)
    {
        for (int currp = 0; currp <= p; ++currp)
        {
            dp[pos][currp] = inf;
            dp[pos][currp] = min(dp[pos][currp], dp[prvBig[pos] - 1][currp] + 1);

            if (currp >= 1)
            {
                dp[pos][currp] = min(dp[pos][currp], dp[pos][currp - 1]);
                dp[pos][currp] = min(dp[pos][currp], dp[prvSmall[pos] - 1][currp - 1]);
            }
        }
    }

    for (int i = 0; i <= p; ++i)
    {
        if (dp[n][i] <= q)
        {
            return true;
        }
    }

    return false;
}

void fastIO()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
}

int main()
{
    fastIO();

    cin >> n >> p >> q;

    for (int i = 1; i <= n; ++i)
    {
        cin >> a[i];
    }

    if (q >= n || p >= n)
    {
        cout << 1 << endl;
        return 0;
    }

    sort(a + 1, a + n + 1);

    int l = 1;
    int r = 1000000000;

    while (l <= r)
    {
        int mid = (l + r) / 2;

        if (check(mid) == true)
        {
            r = mid - 1;
        }
        else
        {
            l = mid + 1;
        }
    }

    cout << l << endl;

    return 0;
}

• Subtask 1: 50 / 50
• Subtask 2: 50 / 50