Submission #464533

#	Time	Username	Problem	Language	Result	Execution time	Memory
464533		SamAnd	Exam (eJOI20_exam)	C++17	12 / 100	30 ms	16264 KiB

exam

#include <bits/stdc++.h>
using namespace std;
#define m_p make_pair
#define all(x) (x).begin(),(x).end()
#define sz(x) ((int)(x).size())
#define fi first
#define se second
typedef long long ll;
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
mt19937 rnf(2106);
const int N = 100005, N0 = 5003;

int n;
int a[N], b[N];

int maxi[N0][N0];

int dp[N0][N0];

bool c[N0][N0];
int rec(int l, int r)
{
    if (l > r)
        return 0;
    if (c[l][r])
        return dp[l][r];
    c[l][r] = true;

    int m = maxi[l][r];

    int dpl = 0;
    int q = 0;
    for (int i = m; i >= l; --i)
    {
        if (b[i] == a[m])
            ++q;
        dpl = max(dpl, q + rec(l, i - 1));
    }

    int dpr = 0;
    q = 0;
    for (int i = m; i <= r; ++i)
    {
        if (b[i] == a[m])
            ++q;
        dpr = max(dpr, q + rec(i + 1, r));
    }

    dp[l][r] = dpl + dpr - (b[m] == a[m]);

    return dp[l][r];
}

int solv0()
{
    for (int l = 1; l <= n; ++l)
    {
        for (int r = l; r <= n; ++r)
        {
            c[l][r] = false;
        }
    }
    for (int l = 1; l <= n; ++l)
    {
        maxi[l][l] = l;
        for (int r = l + 1; r <= n; ++r)
        {
            maxi[l][r] = maxi[l][r - 1];
            if (a[r] > a[maxi[l][r]])
                maxi[l][r] = r;
        }
    }
    return rec(1, n);
}

int p[N];
int ul[N], ur[N];
int solv2()
{
    for (int i = 1; i <= n; ++i)
    {
        p[i] = p[i - 1];
        if (a[i] == b[i])
            ++p[i];
    }

    ul[0] = 0;
    for (int i = 1; i <= n; ++i)
    {
        if (a[i] > b[i])
        {
            ul[i] = i;
        }
        else
        {
            ul[i] = ul[i - 1];
        }
    }
    ur[n + 1] = n + 1;
    for (int i = n; i >= 1; --i)
    {
        if (a[i] > b[i])
        {
            ur[i] = i;
        }
        else
        {
            ur[i] = ur[i + 1];
        }
    }

    int ans = 0;
    for (int i = 1; i <= n; ++i)
    {
        if (a[i] <= b[i])
        {
            if (p[ur[i] - 1] - p[ul[i]] > 0)
                ++ans;
        }
    }

    return ans;
}

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

    if (n <= 5000)
    {
        cout << solv0() << "\n";
        return;
    }

    bool z2 = true;
    for (int i = 1; i <= n; ++i)
    {
        if (b[i] != b[1])
        {
            z2 = false;
            break;
        }
    }

    if (z2)
    {
        cout << solv2() << "\n";
        return;
    }
}

int main()
{
    #ifdef SOMETHING
    freopen("input.txt", "r", stdin);
    //freopen("output.txt", "w", stdout);
    #endif // SOMETHING
    ios_base::sync_with_stdio(false), cin.tie(0);

    /*int st = 100;
    while (st--)
    {
        n = rnf() % 100 + 1;
        for (int i = 1; i <= n; ++i)
        {
            a[i] = rnf() % 100 + 1;
        }
        b[1] = a[rnf() % n + 1];
        for (int i = 2; i <= n; ++i)
            b[i] = b[1];

        if (solv0() != solv2())
        {
            cout << "WA\n";
            return 0;
        }
    }
    cout << "OK\n";
    return 0;*/

    int tt = 1;
    //cin >> tt;
    while (tt--)
    {
        solv();
    }
    return 0;
}

• Subtask 1: 0 / 14
• Subtask 2: 12 / 12
• Subtask 3: 0 / 13
• Subtask 4: 0 / 23
• Subtask 5: 0 / 16
• Subtask 6: 0 / 22