Submission #682050

#	Time	Username	Problem	Language	Result	Execution time	Memory
682050		Kahou	Building 4 (JOI20_building4)	C++14	100 / 100	220 ms	24864 KiB

building4

/* In the name of God, aka Allah */
// let this be mytemp.cpp
#include<bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define endl '\n'
#define mk make_pair
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;

const int N = 2e6 + 50;
int n, a[N];
pii dp[N];

void solve() {
	cin >> n;
	n <<= 1;
	for (int i = 1; i <= n; i++) {
		cin >> a[i<<1];
	}
	for (int i = 1; i <= n; i++) {
		cin >> a[i<<1|1];
	}
	dp[n<<1] = {0, 0};
	dp[n<<1|1] = {1, 1};
	for (int i = (n<<1)-1; i >= 0; i--) {
		dp[i] = {N, -N};
		int x = i+2, y = x^1;
		if (a[i] <= a[x]) {
			dp[i].F = min(dp[i].F, dp[x].F+(i&1));
			dp[i].S = max(dp[i].S, dp[x].S+(i&1));
		}
		if (a[i] <= a[y]) {
			dp[i].F = min(dp[i].F, dp[y].F+(i&1));
			dp[i].S = max(dp[i].S, dp[y].S+(i&1));
		}
	}
	if (dp[0].F > n/2 || dp[0].S < n/2) return cout << -1 << endl, void();

	int cur = n/2;
	int u = 0;
	for (int x = 1; x <= n; x++) {
		if (a[u] <= a[x<<1] && dp[x<<1].F <= cur && cur <= dp[x<<1].S) {
			cout << 'A';
			u = x<<1;
		}
		else {
			cout << 'B';
			u = x<<1|1;
			cur--;
		}
	}
	cout << endl;
}
int main() {
	ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
	solve();
	return 0;
}

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