Submission #212153

#	Time	Username	Problem	Language	Result	Execution time	Memory
212153		losmi247	Building 4 (JOI20_building4)	C++14	0 / 100	6 ms	512 KiB

building4

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 2005;

int n,a[N],b[N];
bool dp[4005][2005][2];

void resimali(){
    dp[1][0][1] = dp[1][1][0] = 1;
    for(int i = 2; i <= 2*n; i++){
        for(int j = 0; j <= n; j++){ /// br A-ova
            if(a[i-1] <= a[i] && j >= 1){
                dp[i][j][0] |= dp[i-1][j-1][0];
            }
            if(b[i-1] <= a[i] && j >= 1){
                dp[i][j][0] |= dp[i-1][j-1][1];
            }
            if(a[i-1] <= b[i]){
                dp[i][j][1] |= dp[i-1][j][0];
            }
            if(b[i-1] <= b[i]){
                dp[i][j][1] |= dp[i-1][j][1];
            }
        }
    }
    if(!dp[2*n][n][0] && !dp[2*n][n][1]){
        cout << -1 << endl;
        return;
    }
    int i = 2*n,j = n,k = -1;
    string ans;
    a[2*n+1] = b[2*n+1] = 2000000000;
    while(i){
        if(dp[i][j][0] && a[i] <= (k == 0 ? a[i+1] : b[i+1])){
            k = 0;
        }
        else{
            k = 1;
        }
        if(k == 0){
            ans += 'A';
            j--;
        }
        else{
            ans += 'B';
        }
        i--;
    }
    reverse(ans.begin(),ans.end());
    cout << ans << endl;
}

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];
    }
    if(n <= 2000){
        resimali();
    }
}

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