Submission #463396

#	Time	Username	Problem	Language	Result	Execution time	Memory
463396		tengiz05	Exam (eJOI20_exam)	C++17	12 / 100	72 ms	4812 KiB

exam

#include <bits/stdc++.h>

using i64 = long long;

constexpr int N = 5005;

int par[N][2 * N];

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    
    int n;
    std::cin >> n;
    std::vector<int> a(n), b(n);
    for (int i = 0; i < n; i++) {
        std::cin >> a[i];
    }
    for (int i = 0; i < n; i++) {
        std::cin >> b[i];
    }
    auto c = a;
    c.insert(c.end(), b.begin(), b.end());
    std::sort(c.begin(), c.end());
    c.erase(std::unique(c.begin(), c.end()), c.end());
    
    for (int i = 0; i < n; i++) {
        a[i] = std::lower_bound(c.begin(), c.end(), a[i]) - c.begin();
        b[i] = std::lower_bound(c.begin(), c.end(), b[i]) - c.begin();
    }
    
    if (n <= 5000) {
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < int(c.size()); j++) {
                par[i + 1][j] = par[i][j] + (b[i] == j);
            }
        }
        
        std::vector<int> pref(n + 1), suf(n + 1);
        for (int i = 0; i < n; i++) {
            pref[i + 1] = pref[i] + (a[i] == b[i]);
        }
        
        std::vector<int> dp(n + 1);
        for (int i = 1; i <= n; i++) {
            dp[i] = dp[i - 1] + (a[i - 1] == b[i - 1]);
            for (int j = i, mx = 0; j >= 1; j--) {
                mx = std::max(mx, a[j - 1]);
                dp[i] = std::max(dp[i], dp[j - 1] + par[i][mx] - par[j - 1][mx]);
            }
        }
        
        std::cout << dp[n] << "\n";
    } else {
        if (std::count(b.begin(), b.end(), b[0]) == n) {
            std::vector<int> t(n, 0);
            for (int i = 0; i < n; i++) {
                if (a[i] == b[0]) {
                    int j = i;
                    while (j >= 0 && a[j] <= b[0] && !t[j]) {
                        t[j--] = 1;
                    }
                    j = i + 1;
                    while (j < n && a[j] <= b[0] && !t[j]) {
                        t[j++] = 1;
                    }
                }
            }
            std::cout << std::accumulate(t.begin(), t.end(), 0) << "\n";
        } else {
            
        }
    }
    
    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