Submission #1091524

#	Time	Username	Problem	Language	Result	Execution time	Memory
1091524		coldbr3w	Building 4 (JOI20_building4)	C++17	100 / 100	188 ms	68936 KiB

building4

#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define pll pair<long long, long long>
#define pb push_back
#define F first
#define S second  
#define all(x) (x).begin(), (x).end()

const ll N = 1e6 + 100;
const ll inf = 1e18;
const ll mod = 1e9 + 7;
const ll block = 350;
ll n;
ll a[N][2];
pll dp[N][2];
void to_thic_cau(){
    cin >> n;
    for(int i = 1; i <= 2 * n;i++) cin >> a[i][0];
    for(int i = 1; i <= 2 * n;i++) cin >> a[i][1];
    dp[0][0] = dp[0][1] = {0, 0};
    for(int i = 1; i <= 2 * n;i++){
        dp[i][0] = dp[i][1] = {-1, -1};
        for(int j = 0; j <= 1;j++){
            if(dp[i-1][j].F != -1){
                for(int k = 0; k <= 1;k++){
                    if(a[i-1][j] <= a[i][k]){
                        pll cur = dp[i-1][j];
                        cur.F += k, cur.S += k;
                        if(dp[i][k].F == -1) dp[i][k] = cur;
                        else dp[i][k].F = min(dp[i][k].F, cur.F), dp[i][k].S = max(dp[i][k].S, cur.S);
                    }
                }
            }
        }
    }
    ll st = -1;
    for(int j = 0; j <= 1;j++){
        if(dp[2 * n][j].S >= n && dp[2 * n][j].F <= n) st = j;
    }
    if(st == -1){
        cout << -1 << '\n';
        return;
    }
    string ans;
    ll cnt = 0;
    for(int i = 2 * n; i >= 1;i--){
        ans.pb('A' + st);
        cnt += st;
        for(int j = 0; j <= 1;j++) if(a[i-1][j] <= a[i][st]){
            if(dp[i-1][j].F + cnt <= n && dp[i-1][j].S + cnt >= n){
                st = j;
                break;
            }
        }
    }
    reverse(all(ans));
    cout << ans << '\n';
}

signed main()   
{  
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    ll tc = 1;
    //cin >> tc;
    while(tc--) to_thic_cau();
}

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