Submission #1170811

#	Time	Username	Problem	Language	Result	Execution time	Memory
1170811		hainam2k9	Building 4 (JOI20_building4)	C++20	0 / 100	1 ms	328 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;
pair<int,int> p[MAXN],dp[MAXN][2];
vector<char> v;
void add(pair<int,int>& a, pair<int,int> b){
    if(b.fi==-1||b.se==-1) return;
    if(a.fi==-1||a.se==-1) return a=b, void();
    a.fi=min(a.fi,b.fi), a.se=max(a.se,b.se);
}
int check(int pos, int cnt){
    if(dp[pos][0].fi<=cnt&&cnt<=dp[pos][0].se) return 0;
    if(dp[pos][1].fi<=cnt&&cnt<=dp[pos][1].se) return 1;
    return 2;
}
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[i][0]=dp[i][1]={-1,-1};
    }
    dp[1][0]={0,0};
    dp[1][1]={1,1};
    for(int i = 2; i<=n<<1; ++i){
        if(p[i].fi>=p[i-1].fi) add(dp[i][0],dp[i-1][0]);
        if(p[i].fi>=p[i-1].se) add(dp[i][0],dp[i-1][1]);
        if(p[i].se>=p[i-1].fi) add(dp[i][1],{dp[i-1][0].fi+1,dp[i-1][0].se+1});
        if(p[i].se>=p[i-1].se) add(dp[i][1],{dp[i-1][1].fi+1,dp[i-1][1].se+1});
    }
    if(check(n<<1,n)==2) return cout << -1, 0;
    for(int i=n<<1, cnt=n; i>0; --i){
        if(check(i,cnt)==0) 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:38:45: note: in expansion of macro 'fo'
   38 |     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:38:45: note: in expansion of macro 'fo'
   38 |     if(fopen((NAME + ".INP").c_str(), "r")) fo;
      |                                             ^~

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