Submission #1104219

#	Time	Username	Problem	Language	Result	Execution time	Memory
1104219		manhlinh1501	Exam (eJOI20_exam)	C++17	77 / 100	94 ms	103320 KiB

exam

#include<bits/stdc++.h>
using namespace std;
using i64 = long long;
const int MAXN = 2e5 + 5;
#define left ___left
#define right ___right
#define ALL(a) (a).begin(), (a).end()

using pii = pair<int, int>;
int N;
int a[MAXN];
int b[MAXN];
int left[MAXN];
int right[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 cnt[MAXN];

    void solution() {
        if(is_subtask() == false) return;
        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 dp[MAXN][MAXN];

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

namespace subtask4 {
    bool is_subtask() {
        vector<int> b;
        for(int i = 1; i <= N; i++) b.emplace_back(a[i]);
        sort(ALL(b));
        for(int i = 1; i < N; i++) {
            if(b[i] == b[i - 1]) return false;
        }
        return true;
    }

    namespace BIT {
        int N;
        int tree[MAXN];

        void init(int _N) {
            N = _N;
        }
        void update(int x, int v) {
            for(; x <= N; x += (x & -x))
                tree[x] = max(tree[x], v);
        }

        int get(int x) {
            int res = 0;
            for(; x; x -= (x & -x))
                res = max(res, x);
            return res;
        }
    }

    int pos[MAXN];

    void solution() {
        if(is_subtask() == false) return;
        BIT::init(N);
        for(int i = 1; i <= N; i++) pos[a[i]] = i;
        int ans = 0;
        for(int i = 1; i <= N; i++) {
            int p = pos[b[i]];
            int x = BIT::get(p) + 1;
            BIT::update(p, x);
            if(left[i] <= p and p <= right[i])
                ans = max(ans, x);
        }
        cout << ans;
        exit(0);
    }
}

namespace subtask6 {
    const int MAXN = 5e3 + 5;

    int dp[MAXN][MAXN];

    bool is_subtask() {
        return N < MAXN;
    }

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

signed main() {
#define task "code"
    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();
    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]--;
    }
    subtask2::solution();
    subtask3::solution();
//    subtask4::solution();
    subtask6::solution();
    return (0 ^ 0);
}

Compilation message (stderr)

exam.cpp: In function 'int main()':
exam.cpp:158:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  158 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
exam.cpp:159:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  159 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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