Submission #893717

#	Time	Username	Problem	Language	Result	Execution time	Memory
893717		noiaint	Exam (eJOI20_exam)	C++17	12 / 100	25 ms	14696 KiB

exam

#include <bits/stdc++.h>

using namespace std;

#define all(x) x.begin(), x.end()

const int N = 1e6 + 5;

bool maxi(int &x, int y) {
    if (x < y) {
        x = y;
        return true;
    }
    return false;
}

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

namespace task2 {

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

int d[N];

void solve() {
    for (int i = 1; i <= n; ++i) if (a[i] == b[1]) {
        int x = l[i] + 1;
        int y = r[i] - 1;
        d[x]++;
        d[y + 1]--;
    }

    for (int i = 1; i <= n; ++i) d[i] += d[i - 1];
    int ans = 0;
    for (int i = 1; i <= n; ++i) ans += d[i] != 0;

    cout << ans;
}

}


namespace task4 {

bool check() {
    set<int> s;
    for (int i = 1; i <= n; ++i) s.insert(a[i]);
    return (s.size() == n);
}

int bit[N];

void update(int u, int c) {
    for (; u < N; u += u & -u) maxi(bit[u], c);
}
int get(int u) {
    int res = 0;
    for (; u > 0; u -= u & -u) maxi(res, bit[u]);
    return res;
}

map<int, int> pos;

void solve() {
    for (int i = 1; i <= n; ++i) pos[a[i]] = i;


    for (int i = 1; i <= n; ++i) {
        auto it = pos.find(b[i]);
        if (it == pos.end()) continue;

        int x = pos[b[i]];

        if (l[x] < i && i < r[x]) {
            int cur = get(i - 1) + 1;
            update(i, cur);
        }
    }

    cout << get(n);

}

}

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

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

    stack<int> st;
    for (int i = 1; i <= n; ++i) {
        while (st.size() && a[i] >= a[st.top()]) st.pop();
        l[i] = st.size() ? st.top() : 0;
        st.push(i);
    }
    st = stack<int> {};
    for (int i = n; i >= 1; --i) {
        while (st.size() && a[i] >= a[st.top()]) st.pop();
        r[i] = st.size() ? st.top() : n + 1;
        st.push(i);
    }

    if (task2::check()) return task2::solve(), 0;
    if (task4::check()) return task4::solve(), 0;


    return 0;
}

Compilation message (stderr)

exam.cpp: In function 'bool task4::check()':
exam.cpp:55:22: warning: comparison of integer expressions of different signedness: 'std::set<int>::size_type' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   55 |     return (s.size() == n);
      |             ~~~~~~~~~^~~~

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