Submission #465571

#	Time	Username	Problem	Language	Result	Execution time	Memory
465571		Sench2006	Exam (eJOI20_exam)	C++14	36 / 100	134 ms	7620 KiB

exam

#include <bits/stdc++.h>
#include <unordered_map>
using namespace std;

#define ll long long
#define ar array

#define fastio ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);

// --------------- SOLUTION --------------- //

const int N = 1e5+5;
int n;
int a[N], b[N];
int nm[N], pm[N];

void pre() {
    stack<int> s;
    for (int i = 1; i <= n; ++i) {
        while (!s.empty() && a[s.top()] <= a[i])
            s.pop();
        if (s.empty())
            pm[i] = 0;
        else
            pm[i] = s.top();
        s.push(i);
    }
    while (!s.empty())
        s.pop();
    for (int i = n; i >= 1; --i) {
        while (!s.empty() && a[s.top()] <= a[i])
            s.pop();
        if (s.empty())
            nm[i] = n + 1;
        else
            nm[i] = s.top();
        s.push(i);
    }
}

int t[N * 4];
void ubd(int tl, int tr, int x, int y, int pos)
{
    if (tl == tr)
    {
        t[pos] = y;
        return;
    }
    int m = (tl + tr) / 2;
    if (x <= m)
        ubd(tl, m, x, y, pos * 2);
    else
        ubd(m + 1, tr, x, y, pos * 2 + 1);
    t[pos] = max(t[pos * 2], t[pos * 2 + 1]);
}
 
int qry(int tl, int tr, int l, int r, int pos)
{
    if (l > r)
        return 0;
    if (tl == l && tr == r)
        return t[pos];
    int m = (tl + tr) / 2;
    return max(qry(tl, m, l, min(m, r), pos * 2),
               qry(m + 1, tr, max(m + 1, l), r, pos * 2 + 1));
}
 
map <int, int> mp;
int segTreeSolve() {
    for (int i = 1; i <= n; ++i)
        mp[a[i]] = i;
 
    for (int i = 1; i <= n; ++i) {
        if (mp.find(b[i]) == mp.end())
            continue;
        int x = mp[b[i]];
        if (pm[x] < i && i < nm[x]) {
            ubd(1, n, x, qry(1, n, 1, x, 1) + 1, 1);
        }
    }
    return t[1];
}

void solve() { 
    cin >> n;
    for (int i = 1; i <= n; ++i)
        cin >> a[i];
    for (int i = 1; i <= n; ++i)
        cin >> b[i];
 
    pre();
    cout << segTreeSolve() << "\n";
}

int main() {
    fastio;
    // fileio;
    int tests = 1;
    // cin >> tests;
    while (tests--) {
        solve();
    }

    return 0;
}

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