Submission #1104002

#	Time	Username	Problem	Language	Result	Execution time	Memory
1104002		manhlinh1501	Exam (eJOI20_exam)	C++17	12 / 100	63 ms	9520 KiB

exam

#include<bits/stdc++.h>
using namespace std;
using i64 = long long;
const int MAXN = 2e5 + 5;
#define left ___left
#define right ___right
using pii = pair<int, int>;
int N;
int a[MAXN];
int b[MAXN];

void compress() {
    map<int, int> comp;
    for(int i = 1; i <= N; i++) comp[a[i]] = 1;
    for(int i = 1; i <= N; i++) comp[b[i]] = 1;
    int c = 0;
    for(auto &[x, y] : comp) y = ++c;
    for(int i = 1; i <= N; i++) a[i] = comp[a[i]];
    for(int i = 1; i <= N; i++) b[i] = comp[b[i]];
}

namespace subtask2 {
    bool is_subtask() {
        for(int i = 1; i < N; i++) {
            if(b[i] != b[i + 1]) return false;
        }
        return true;
    }
    int left[MAXN];
    int right[MAXN];
    int cnt[MAXN];

    void solution() {
        if(is_subtask() == false) return;
        for(int i = 1; i <= N; i++) {
            left[i] = i - 1;
            while(left[i] > 0 and a[left[i]] <= a[i])
                left[i] = left[left[i]];
        }
        for(int i = N; i >= 1; i--) {
            right[i] = i + 1;
            while(right[i] <= N and a[right[i]] <= a[i])
                right[i] = right[right[i]];
        }
        for(int i = 1; i <= N; i++) {
            left[i]++;
            right[i]--;
        }
        for(int i = 1; i <= N; i++) {
            if(a[i] == b[i]) {
                cnt[left[i]]++;
                cnt[right[i] + 1]--;
            }
        }
        for(int i = 1; i <= N; i++) cnt[i] += cnt[i - 1];
        int ans = 0;
        for(int i = 1; i <= N; i++) ans += (cnt[i] > 0);
        cout << ans;
        exit(0);
    }
}

namespace subtask3 {
    const int MAXN = 5e3 + 5;
    bool is_subtask() {
        return is_sorted(a + 1, a + N + 1);
    }
    int cnt[MAXN][MAXN];
    int dp[MAXN];

    void solution() {
        if(is_subtask() == false) return;
        for(int i = 1; i <= N; i++) {
            for(int j = 1; j <= N; j++)
                cnt[i][j] = cnt[i][j - 1] + (a[i] == b[j]);
        }
        for(int i = 1; i <= N; i++) {
            for(int j = 1; j <= i; j++)
                dp[i] = max(dp[i], dp[j - 1] + (cnt[i][i] - cnt[i][j - 1]));
        }
        cout << *max_element(dp + 1, dp + N + 1);
        exit(0);
    }
}

signed main() {
#define task ""
    if(fopen(task".inp", "r")) {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> N;
    for(int i = 1; i <= N; i++) cin >> a[i];
    for(int i = 1; i <= N; i++) cin >> b[i];
    compress();
    subtask2::solution();
    subtask3::solution();
    return (0 ^ 0);
}

Compilation message (stderr)

exam.cpp: In function 'int main()':
exam.cpp:89:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   89 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
exam.cpp:90:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   90 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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