Submission #751317

#	Time	Username	Problem	Language	Result	Execution time	Memory
751317		Sam_a17	Building 4 (JOI20_building4)	C++17	0 / 100	2055 ms	340 KiB

building4

#define _CRT_SECURE_NO_WARNINGS
#include <bits/stdc++.h>
//#include "temp.cpp"
#include <cstdio>
using namespace std;
 
#ifndef ONLINE_JUDGE
#define dbg(x) cerr << #x <<" "; print(x); cerr << endl;
#else
#define dbg(x)
#endif
 
#define sz(x) (int((x).size()))
#define len(x) (int)x.length()
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define clr(x) (x).clear()
#define uniq(x) x.resize(unique(all(x)) - x.begin());
 
#define pb push_back
#define popf pop_front
#define popb pop_back
#define ld long double
#define ll long long
 
void print(long long t) {cerr << t;}
void print(int t) {cerr << t;}
void print(string t) {cerr << t;}
void print(char t) {cerr << t;}
void print(double t) {cerr << t;}
void print(unsigned long long t) {cerr << t;}
void print(long double t) {cerr << t;}
 
template <class T, class V> void print(pair <T, V> p);
template <class T> void print(vector <T> v);
template <class T> void print(set <T> v);
template <class T, class V> void print(map <T, V> v);
template <class T> void print(multiset <T> v);
template <class T> void print(T v[],T n) {cerr << "["; for(int i = 0; i < n; i++) {cerr << v[i] << " ";} cerr << "]";}
template <class T, class V> void print(pair <T, V> p) {cerr << "{"; print(p.first); cerr << ","; print(p.second); cerr << "}";}
template <class T> void print(vector <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(deque <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(set <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T> void print(multiset <T> v) {cerr << "[ "; for (T i : v) {print(i); cerr << " ";} cerr << "]";}
template <class T, class V> void print(map <T, V> v) {cerr << "[ "; for (auto i : v) {print(i); cerr << " ";} cerr << "]";}
 
#include <ext/pb_ds/assoc_container.hpp>
using namespace __gnu_pbds;
#define nl '\n'

// for random generations
mt19937 myrand(chrono::steady_clock::now().time_since_epoch().count());
// mt19937 myrand(131);

// for grid problems
int dx[8] = {-1,0,1,0,1,-1,1,-1};
int dy[8] = {0,1,0,-1,1,1,-1,-1};
 
// lowest / (1 << 17) >= 1e5 / (1 << 18) >= 2e5 / (1 << 21) >= 1e6
void fastIO() {
  ios_base::sync_with_stdio(false);
  cin.tie(nullptr); cout.tie(nullptr);
}
// file in/out
void setIO(string str = "") {
  fastIO();
 
  if (str != "") {
    freopen((str + ".in").c_str(), "r", stdin);
    freopen((str + ".out").c_str(), "w", stdout);
  }
}
 
// Indexed Set
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
const int N = 2e3 + 10;
int dp[N][N / 2][2];
int n, a[N], b[N];

pair<pair<int, int>, int> prv[N][N / 2][2];

string cont(int i, int j, int k) {
  string answ = "";

  while(i) {
    if(k == 1) {
      answ += "A";
    } else {
      answ += "B";
    }

    auto u = prv[i][j][k];
    i = u.first.first;
    j = u.first.second;
    k = u.second;
  }

  reverse(all(answ));
  return answ;
}

void solve_() {
  cin >> n;
  
  for(int i = 1; i <= 2 * n; i++) {
    cin >> a[i];
  }
  
  for(int i = 1; i <= 2 * n; i++) {
    cin >> b[i];
  }

  dp[1][1][1] = 1;
  dp[1][0][0] = 1;

  for(int i = 1; i < 2 * n; i++) {
    for(int j = 0; j <= min(i, n); j++) {
      if(j < n) {
        int ok = 0;
        dp[i + 1][j + 1][1] |= dp[i][j][1] & (a[i] <= a[i + 1]);
        if(dp[i + 1][j + 1][1]) {
          prv[i + 1][j + 1][1] = make_pair(make_pair(i, j), 1);
          ok = 1;
        }
        dp[i + 1][j + 1][1] |= dp[i][j][0] & (b[i] <= a[i + 1]);
        if(dp[i + 1][j + 1][1] && !ok) {
          prv[i + 1][j + 1][1] = make_pair(make_pair(i, j), 0);
        }
      }

      if((i - j) < n) {
        int ok = 0;
        dp[i + 1][j][0] |= dp[i][j][1] & (a[i] <= b[i + 1]);
        if(dp[i + 1][j][0]) {
          prv[i + 1][j][0] = make_pair(make_pair(i, j), 1);
          ok = 1;
        }
        dp[i + 1][j][0] |= dp[i][j][0] & (b[i] <= b[i + 1]);
        if(dp[i + 1][j][0] && !ok) {
          prv[i + 1][j][0] = make_pair(make_pair(i, j), 0);
        }
      }
    }
  }


  if(dp[2 * n][n][0]) {
    cout << cont(2 * n, n, 0) << '\n';
  } else if(dp[2 * n][n][1]) {
    cout << cont(2 * n, n, 1) << '\n';
  } else {
    cout << -1 << '\n';
  }
  
}
 
int main() {
  setIO();
  
  auto solve = [&](int test_case)-> void {
    while(test_case--) {
      solve_();
    }
  };
 
  int test_cases = 1; 
  // cin >> test_cases;
  solve(test_cases);
 
  return 0;
}

Compilation message (stderr)

building4.cpp: In function 'void setIO(std::string)':
building4.cpp:69:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   69 |     freopen((str + ".in").c_str(), "r", stdin);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
building4.cpp:70:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   70 |     freopen((str + ".out").c_str(), "w", stdout);
      |     ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 0 / 11
• Subtask 2: 0 / 89