Submission #382845

#	Time	Username	Problem	Language	Result	Execution time	Memory
382845		valerikk	Exam (eJOI20_exam)	C++17	30 / 100	900 ms	524292 KiB

exam

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

int main() {
#ifdef LOCAL
    freopen("input.txt", "r", stdin);
#endif
    ios::sync_with_stdio(false);
    cin.tie(0);
    int n;
    cin >> n;
    vector<int> a(n);
    for (int i = 0; i < n; i++) cin >> a[i];
    vector<int> b(n);
    for (int i = 0; i < n; i++) cin >> b[i];
    
    vector<int> right(n, n);
    vector<int> st;
    for (int i = 0; i < n; i++) {
        while (!st.empty() && a[st.back()] < a[i]) {
            right[st.back()] = i;
            st.pop_back();
        }
        st.push_back(i);
    }
    
    vector<int> left(n, -1);
    st = {};
    for (int i = n - 1; i >= 0; i--) {
        while (!st.empty() && a[st.back()] < a[i]) {
            left[st.back()] = i;
            st.pop_back();
        }
        st.push_back(i);
    }
    
    vector<pair<pair<int, int>, int>> events;
    for (int i = 0; i < n; i++) {
        for (int l = left[i] + 1; l < right[i]; l++) {
            int cnt = 0;
            for (int r = l; r < right[i]; r++) {
                if (b[r] == a[i]) cnt++;
                events.push_back({{l, r}, cnt});
            }
        }
    }
    
    vector<int> dp(n + 1, 0);
    for (auto e : events) {
        int l = e.first.first, r = e.first.second, cnt = e.second;
        dp[r + 1] = max(dp[r + 1], dp[l] + cnt);
    }
    
    cout << dp[n] << endl;
    return 0;
}

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