Submission #1213066

#	Time	Username	Problem	Language	Result	Execution time	Memory
1213066		siewjh	Building 4 (JOI20_building4)	C++20	100 / 100	147 ms	28812 KiB

building4

#include <bits/stdc++.h>
using namespace std;
const int MAXN = 1000005;
int arr[MAXN][2], mna[MAXN][2], mxa[MAXN][2];
int main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int nums; cin >> nums;
	for (int j = 0; j <= 1; j++)
		for (int i = 1; i <= nums << 1; i++)
			cin >> arr[i][j];
	for (int i = 1; i <= nums << 1; i++){
		for (int j = 0; j <= 1; j++){
			int mn = 2 * MAXN, mx = -MAXN;
			for (int k = 0; k <= 1; k++)
				if (arr[i][j] >= arr[i - 1][k]){
					mn = min(mn, mna[i - 1][k]);
					mx = max(mx, mxa[i - 1][k]);
				}
			mn += j; mx += j;
			mna[i][j] = mn; mxa[i][j] = mx;
		}
	}
	int req = nums, curr = -1;
	vector<int> ans(nums << 1);
	for (int i = nums << 1; i >= 1; i--){
		for (int j = 0; j <= 1; j++){
			if (i != nums << 1 && arr[i][j] > arr[i + 1][curr]) continue;
			if (mna[i][j] <= req && mxa[i][j] >= req){
				curr = j; break;
			}
		}
		if (curr == -1){
			cout << -1; return 0;
		}
		req -= curr; ans[i - 1] = curr;
	}
	for (int x : ans) cout << (char)('A' + x);
}

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