Submission #568492

#	Time	Username	Problem	Language	Result	Execution time	Memory
568492		losmi247	Building 4 (JOI20_building4)	C++14	0 / 100	3 ms	412 KiB

building4

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 1e6+56;

int n,a[N],b[N],c[N];

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cin >> n;
    for(int i = 1; i <= 2*n; i++){
        cin >> a[i];
    }
    for(int i = 1; i <= 2*n; i++){
        cin >> b[i];
    }

    string s = "";
    int cnta = 0;
    for(int i = 1; i <= 2*n; i++){
        if(a[i] < b[i]){
            if(a[i] >= c[i-1]){
                s += "A";
                cnta++;
                c[i] = a[i];
            }
            else{
                if(b[i] < c[i-1]){
                    cout << -1 << endl;
                    return 0;
                }
                s += "B";
                c[i] = b[i];
            }
        }
        else{
            if(b[i] >= c[i-1]){
                s += "B";
                c[i] = b[i];
            }
            else{
                if(a[i] < c[i-1]){
                    cout << -1 << endl;
                    return 0;
                }
                s += "A";
                cnta++;
                c[i] = a[i];
            }
        }
    }

    //cout << "pre " << s << " " << cnta << endl;

    if(cnta > n){
        for(int i = 2*n; i >= 1; i--){
            if(cnta == n) break;
            if(s[i-1] == 'B') continue;
            if((i == 1 || b[i] >= c[i-1]) && (i == 2*n || b[i] <= c[i+1])){
                cnta--;
                c[i] = b[i];
                s[i-1] = 'B';
            }
        }
        if(cnta != n){
            cout << -1 << endl;
            return 0;
        }
    }
    else if(cnta < n){
        for(int i = 2*n; i >= 1; i--){
            if(cnta == n) break;
            if(s[i-1] == 'A') continue;
            if((i == 1 || a[i] >= c[i-1]) && (i == 2*n || a[i] <= c[i+1])){
                cnta++;
                c[i] = a[i];
                s[i-1] = 'A';
            }
        }
        if(cnta != n){
            cout << -1 << endl;
            return 0;
        }
    }

    cout << s << endl;
}

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