Submission #1210776

#	Time	Username	Problem	Language	Result	Execution time	Memory
1210776		sunflower	Exam (eJOI20_exam)	C++17	65 / 100	254 ms	99388 KiB

exam

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

#define BIT(x, i) (((x) >> (i)) & 1)

template <class X, class Y>
  bool maximize(X &x, Y y) {
    if (x < y) return x = y, true;
    else return false;
  }

template <class T>
  void remove_dup(vector <T> &v) {
    sort(v.begin(), v.end());
    v.resize(unique(v.begin(), v.end()) - v.begin());
  }
  int POS(int x, vector <int> &v) {
    return lower_bound(v.begin(), v.end(), x) - v.begin() + 1;
  }

const int inf = (int) 1e9 + 7;

int n;

#define MAX_N 100'100
int a[MAX_N + 2], b[MAX_N + 2];

#undef MAX_N

namespace subtask2 {
  bool check() {
    return (*max_element(b + 1, b + 1 + n) == *min_element(b + 1, b + 1 + n));
  }

  void solve() {
    int ans = 0, cnt = 0;
    bool ok = false;
    a[n + 1] = inf;
    for (int i = 1; i <= n + 1; ++i) {
      if (a[i] > b[1]) {
        if (ok) ans += cnt;
        cnt = 0;
        ok = false;
      } else {
        ++cnt;
        if (a[i] == b[1]) ok = true;
      }
    }

    cout << ans;
  }
};

namespace subtask3 {
  bool check() {
    for (int i = 1; i < n; ++i) {
      if (a[i] >= a[i + 1]) return false;
    }
    return (n <= 5000);
  }

  int f[5050][5050];
  //f[i][j]: ap dung nhung thay doi tu A[1] -> A[i] cho nhung thang tu 1 -> j

  void solve(){
    int N = n;
    vector <int> lef(n + 2), rig(n + 2);
    for(int i = 1; i <= N; i++){
        lef[i] = i - 1;
        while(lef[i] > 0 && a[i] >= a[lef[i]]) lef[i] = lef[lef[i]];
    }
    for(int i = N; i >= 1; i--){
        rig[i] = i + 1;
        while(rig[i] <= N && a[i] >= a[rig[i]]) rig[i] = rig[rig[i]];
    }

      int ans = 0;
      for(int j = 1; j <= n; j++){
        for(int i = 1; i <= n; i++){
              f[i][j] = max(f[i - 1][j], f[i][j - 1]);
              if(a[i] == b[j] && lef[i] < j && j < rig[i]){
                  maximize(f[i][j], f[i][j - 1] + 1);
              }
              maximize(ans, f[i][j]);
          }
      }

      cout << ans << '\n';
  }

};

int main() {
  ios_base::sync_with_stdio(false);cin.tie(nullptr);
  if (fopen("test.inp","r")) {
    freopen("test.inp","r",stdin);
    freopen("test.out","w",stdout);
  }
  cin >> n;
  vector <int> v;
  for (int i = 1; i <= n; ++i) cin >> a[i], v.push_back(a[i]);
  for (int i = 1; i <= n; ++i) cin >> b[i], v.push_back(b[i]);

  remove_dup(v);
  for (int i = 1; i <= n; ++i) {
    a[i] = POS(a[i], v);
    b[i] = POS(b[i], v);
  }

//  if (subtask2 :: check()) return subtask2 :: solve(), 0;
//  if (subtask3 :: check())
    return subtask3 :: solve(), 0;

  return 0;
}

Compilation message (stderr)

exam.cpp: In function 'int main()':
exam.cpp:96:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   96 |     freopen("test.inp","r",stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
exam.cpp:97:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   97 |     freopen("test.out","w",stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~

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