Submission #1164381

#	Time	Username	Problem	Language	Result	Execution time	Memory
1164381		hainam2k9	Building 4 (JOI20_building4)	C++20	11 / 100	154 ms	24012 KiB

building4

#include <bits/stdc++.h>
#define tt cin.tie(0), cout.tie(0), ios_base::sync_with_stdio(0)
#define fo freopen((NAME+".INP").c_str(), "r", stdin), freopen((NAME+".OUT").c_str(), "w", stdout)
#define ll long long
#define ull unsigned long long
#define i128 __int128
#define db long double
#define sz(a) ((int)(a).size())
#define pb emplace_back
#define pf emplace_front
#define pob pop_back
#define pof pop_front
#define lb lower_bound
#define ub upper_bound
#define fi first
#define se second
#define ins emplace
#define mp make_pair
using namespace std;
const int MOD = 1e9+7, MAXN = 1e6+5;
const string NAME = "";
int n;
bool dp[4005][2005][2];
pair<int,int> p[MAXN];
vector<char> v;
int main()
{
    tt;
    if(fopen((NAME + ".INP").c_str(), "r")) fo;
    cin >> n;
    for(int i = 1; i<=n<<1; ++i)
        cin >> p[i].fi;
    for(int i = 1; i<=n<<1; ++i)
        cin >> p[i].se;
    dp[1][0][0]=dp[1][1][1]=1;
    for(int i = 2; i<=n<<1; ++i)
        for(int j = 0; j<=min(i,n); ++j){
            dp[i][j][0]|=dp[i-1][j][0]&(p[i].fi>=p[i-1].fi);
            dp[i][j][0]|=dp[i-1][j][1]&(p[i].fi>=p[i-1].se);
            dp[i][j][1]|=dp[i-1][j-1][0]&(p[i].se>=p[i-1].fi);
            dp[i][j][1]|=dp[i-1][j-1][1]&(p[i].se>=p[i-1].se);
        }
    if(!dp[n<<1][n][0]&&!dp[n<<1][n][1]) return cout << -1, 0;
    for(int i=n<<1, cnt=n; i>0; --i){
        if(dp[i][cnt][0]&&(i==2*n||p[i].fi<=(v.back()=='A' ? p[i+1].fi : p[i+1].se))) v.pb('A');
        else v.pb('B'), --cnt;
    }
    reverse(v.begin(),v.end());
    for(char& c : v) cout << c;
}

Compilation message (stderr)

building4.cpp: In function 'int main()':
building4.cpp:3:19: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    3 | #define fo freopen((NAME+".INP").c_str(), "r", stdin), freopen((NAME+".OUT").c_str(), "w", stdout)
      |            ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
building4.cpp:29:45: note: in expansion of macro 'fo'
   29 |     if(fopen((NAME + ".INP").c_str(), "r")) fo;
      |                                             ^~
building4.cpp:3:63: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
    3 | #define fo freopen((NAME+".INP").c_str(), "r", stdin), freopen((NAME+".OUT").c_str(), "w", stdout)
      |                                                        ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
building4.cpp:29:45: note: in expansion of macro 'fo'
   29 |     if(fopen((NAME + ".INP").c_str(), "r")) fo;
      |                                             ^~

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