Submission #709557

#	Time	Username	Problem	Language	Result	Execution time	Memory
709557		RandomLB	Building 4 (JOI20_building4)	C++17	0 / 100	1 ms	340 KiB

building4

#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f;
#define all(x) x.begin(), x.end()
#define ms(x, a) memset(x, a, sizeof(x))
#define deb(...) logger(#__VA_ARGS__, __VA_ARGS__)
template<typename ...Args>
void logger(string vars, Args&&... values){
    cout << vars << " = ";
    string delim = "";
    (...,(cout << delim << values, delim = ", "));
    cout << endl;
}
//===========================================
const int MAX = 1e6+5;
int a[MAX], b[MAX], dp[2][2][MAX];

int main(){
    cin.tie(0)->sync_with_stdio(0);
    int n; cin >> n; n*=2;
    for (int i = 1; i <= n; i++) cin >> a[i];
    for (int i = 1; i <= n; i++) cin >> b[i];
    for (int i = 1; i <= n; i++){
        dp[0][0][i] = dp[1][0][i] = INF;
        if (a[i] >= a[i-1]){
            dp[0][0][i] = min(dp[0][0][i], dp[0][0][i-1]+1);
            dp[0][1][i] = max(dp[0][1][i], dp[0][1][i-1]+1);
        }
        if (a[i] >= b[i-1]){
            dp[0][0][i] = min(dp[0][0][i], dp[1][0][i-1]+1);
            dp[0][1][i] = max(dp[0][1][i], dp[1][1][i-1]+1);
        }
        if (b[i] >= a[i-1]){
            dp[1][0][i] = min(dp[1][0][i], dp[0][0][i-1]);
            dp[1][1][i] = max(dp[1][1][i], dp[0][1][i-1]);
        }
        if (b[i] >= b[i-1]){
            dp[1][0][i] = min(dp[1][0][i], dp[1][0][i-1]);
            dp[1][1][i] = max(dp[1][1][i], dp[1][1][i-1]);
        }
    }
    //deb(dp[0][0][n], dp[1][0][n], dp[0][1][n], dp[1][1][n]);
    if ((dp[0][0][n] <= n/2 && n/2 <= dp[0][1][n]) ||
        (dp[1][0][n] <= n/2 && n/2 <= dp[1][1][n])){
        string res = "";
        int c = (dp[1][0][n] <= n/2 && n/2 <= dp[1][1][n]);
        int rem = n/2;
        for (int i = n; i; i--){
            res += (c? 'B' : 'A');
            rem -= (!c);
            c = (dp[1][0][i-1] <= rem && rem <= dp[1][1][i-1]);
        }
        assert(!rem);
        reverse(all(res));
        cout << res << "\n";
        return 0;
    }
    cout << -1 << "\n";
}

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