Submission #1027236

#	Time	Username	Problem	Language	Result	Execution time	Memory
1027236		adaawf	Building 4 (JOI20_building4)	C++17	100 / 100	181 ms	48208 KiB

building4

#include <iostream>
using namespace std;
pair<int, int> f[1000005][2];
int a[1000005][2], res[1000005];
int main() {
    ios::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    int n;
    cin >> n;
    for (int i = 1; i <= n * 2; i++) {
        cin >> a[i][0];
    }
    for (int i = 1; i <= n * 2; i++) {
        cin >> a[i][1];
        f[i][0] = f[i][1] = {-1e9, 1e9};
    }
    f[1][0] = {0, 0};
    f[1][1] = {1, 1};
    for (int i = 2; i <= n * 2; i++) {
        if (a[i][0] >= a[i - 1][0]) {
            f[i][0].first = max(f[i][0].first, f[i - 1][0].first);
            f[i][0].second = min(f[i][0].second, f[i - 1][0].second);
        }
        if (a[i][0] >= a[i - 1][1]) {
            f[i][0].first = max(f[i][0].first, f[i - 1][1].first);
            f[i][0].second = min(f[i][0].second, f[i - 1][1].second);
        }
        if (a[i][1] >= a[i - 1][0]) {
            f[i][1].first = max(f[i][1].first, f[i - 1][0].first + 1);
            f[i][1].second = min(f[i][1].second, f[i - 1][0].second + 1);
        }
        if (a[i][1] >= a[i - 1][1]) {
            f[i][1].first = max(f[i][1].first, f[i - 1][1].first + 1);
            f[i][1].second = min(f[i][1].second, f[i - 1][1].second + 1);
        }
    }
    int flag = -1;
    if (f[n * 2][0].first >= n && f[n * 2][0].second <= n) flag = 0;
    else if (f[n * 2][1].first >= n && f[n * 2][1].second <= n) flag = 1;
    if (flag == -1) {
        cout << -1;
        return 0;
    }
    int h = n * 2, c = n;
    while (h) {
        res[h] = flag;
        c -= flag;
        for (int j = 0; j < 2; j++) {
            if (a[h - 1][j] <= a[h][flag]) {
                if (f[h - 1][j].first >= c && f[h - 1][j].second <= c) {
                    flag = j;
                    break;
                }
            }
        }
        h--;
    }
    for (int i = 1; i <= n * 2; i++) {
        if (res[i] == 0) cout << 'A';
        else cout << 'B';
    }
}

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