Submission #752129

#	Time	Username	Problem	Language	Result	Execution time	Memory
752129		sofija6	Building 4 (JOI20_building4)	C++14	11 / 100	2086 ms	23396 KiB

building4

#include <bits/stdc++.h>
#define ll int
#define MAXN 1000010
#define llinf 1e9
using namespace std;
ll a[2][MAXN],dp[2][MAXN][2];
int main()
{
    ios::sync_with_stdio(false); cin.tie(0); cout.tie(0);
    ll n;
    cin >> n;
    for (ll i=0;i<2;i++)
    {
        for (ll j=1;j<=2*n;j++)
            cin >> a[i][j];
    }
    dp[0][1][0]=dp[0][1][1]=1;
    dp[1][1][0]=dp[1][1][1]=0;
    for (ll i=2;i<=2*n;i++)
    {
        dp[0][i][0]=dp[1][i][0]=llinf;
        dp[0][i][1]=dp[1][i][1]=-llinf;
        for (ll j=0;j<2;j++)
        {
            if (a[0][i]>=a[j][i-1])
            {
                dp[0][i][0]=min(dp[0][i][0],dp[j][i-1][0]+1);
                dp[0][i][1]=max(dp[0][i][1],dp[j][i-1][1]+1);
            }
            if (a[1][i]>=a[j][i-1])
            {
                dp[1][i][0]=min(dp[1][i][0],dp[j][i-1][0]);
                dp[1][i][1]=max(dp[1][i][1],dp[j][i-1][1]);
            }
        }
    }
    if ((dp[0][2*n][0]>n || dp[0][2*n][1]<n) && (dp[1][2*n][0]>n || dp[1][2*n][1]<n))
    {
        cout << -1;
        return 0;
    }
    ll val=n,pos=2*n+1,i=1;
    a[0][pos]=a[1][pos]=llinf;
    string ans="";
    while (pos>1)
    {
        val-=(1-i);
        i=dp[0][pos-1][0]<=val && dp[0][pos-1][1]>=val && a[0][pos-1]<=a[i][pos]?0 : 1;
        ans=(i?"B" : "A")+ans;
        pos--;
    }
    cout << ans;
    return 0;
}

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