Submission #683982

#	Time	Username	Problem	Language	Result	Execution time	Memory
683982		stevancv	Building 4 (JOI20_building4)	C++14	100 / 100	261 ms	48068 KiB

building4

#include <bits/stdc++.h>
#define ll long long
#define ld long double
#define sp ' '
#define en '\n'
#define smin(a, b) a = min(a, b)
#define smax(a, b) a = max(a, b)
using namespace std;
const int N = 1e6 + 2;
const int inf = 1e9;
int a[N][2], dpl[N][2], dpr[N][2], ans[N];
void Resi(int i, int j, int k) {
    if (i == 0) return;
    ans[i] = j;
    k -= j;
    if (dpl[i - 1][0] <= k && k <= dpr[i - 1][0] && a[i - 1][0] <= a[i][j]) Resi(i - 1, 0, k);
    else if (dpl[i - 1][1] <= k && k <= dpr[i - 1][1] && a[i - 1][1] <= a[i][j]) Resi(i - 1, 1, k);
}
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    int n; cin >> n;
    n = 2 * n;
    for (int i = 1; i <= n; i++) cin >> a[i][0];
    for (int i = 1; i <= n; i++) cin >> a[i][1];
    for (int i = 1; i <= n; i++) for (int j = 0; j < 2; j++) dpl[i][j] = inf, dpr[i][j] = -inf;
    dpl[1][0] = dpr[1][0] = 0;
    dpl[1][1] = dpr[1][1] = 1;
    for (int i = 2; i <= n; i++) {
        for (int j = 0; j < 2; j++) {
            for (int pj = 0; pj < 2; pj++) {
                if (a[i - 1][pj] > a[i][j]) continue;
                smin(dpl[i][j], dpl[i - 1][pj] + j);
                smax(dpr[i][j], dpr[i - 1][pj] + j);
            }
        }
    }
    if (dpl[n][0] <= n / 2 && n / 2 <= dpr[n][0]) Resi(n, 0, n / 2);
    else if (dpl[n][1] <= n / 2 && n / 2 <= dpr[n][1]) Resi(n, 1, n / 2);
    else {cout << -1; return 0;}
    for (int i = 1; i <= n; i++) {
        if (ans[i] == 0) cout << 'A';
        if (ans[i] == 1) cout << 'B';
    }
    cout << en;
    return 0;
}

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