Submission #520682

#	Time	Username	Problem	Language	Result	Execution time	Memory
520682		ymm	Building 4 (JOI20_building4)	C++17	100 / 100	243 ms	45236 KiB

building4

///
///   Oh? You're approaching me?
///

#include <bits/stdc++.h>
#define Loop(x,l,r) for(ll x = ll(l); x < ll(r); ++x)
#define LoopR(x,l,r) for(ll x = ll(r)-1; x >= ll(l); --x)
#define Kill(x) exit((cout << (x) << '\n', 0))
typedef long long ll;
typedef std::pair<int,int> pii;
typedef std::pair<ll,ll> pll;
using namespace std;

const int N = 1'000'010;

int dpal[N], dpar[N];
int dpbl[N], dpbr[N];
int a[N], b[N];
int n;

int main()
{
	cin.tie(0) -> sync_with_stdio(false);
	cin >> n; n*=2;
	//Loop(i,0,n) cout << (a[i]=rand()%100) << ' '; cout << '\n';//cin >> a[i];
	//Loop(i,0,n) cout << (b[i]=rand()%100) << ' '; cout << '\n';//cin >> b[i];
	Loop(i,0,n) cin >> a[i];
	Loop(i,0,n) cin >> b[i];
	dpal[0] = 1; dpar[0] = 2;
	dpbl[0] = 0; dpbr[0] = 1;
	Loop(i,1,n){
		int l, r;

		l = min(a[i-1]<=a[i]?dpal[i-1]:N, b[i-1]<=a[i]?dpbl[i-1]:N);
		r = max(a[i-1]<=a[i]?dpar[i-1]:0, b[i-1]<=a[i]?dpbr[i-1]:0);
		if(r) {dpal[i] = l+1; dpar[i] = r+1;} else {dpal[i] = N; dpar[i] = 0;}

		l = min(a[i-1]<=b[i]?dpal[i-1]:N, b[i-1]<=b[i]?dpbl[i-1]:N);
		r = max(a[i-1]<=b[i]?dpar[i-1]:0, b[i-1]<=b[i]?dpbr[i-1]:0);
		dpbl[i] = l; dpbr[i] = r;

		if(!(!dpar[i] || !dpbr[i] || max(dpal[i], dpbl[i]) <= min(dpar[i], dpbr[i]))){
			cout <<"err\n";
		}
//		cout << dpal[i] << ' ' << dpar[i] << '\n';
//		cout << dpbl[i] << ' ' << dpbr[i] << '\n';
//		cout << '\n';
	}
	if(!(dpal[n-1] <= n/2 && n/2 < dpar[n-1]) && !(dpbl[n-1] <= n/2 && n/2 < dpbr[n-1]))
		Kill(-1);
	int k=n/2, lst=1e9+10;
	string ans;
	LoopR(i,0,n){
		if(dpal[i] <= k && k < dpar[i] && a[i]<=lst){
			ans.push_back('A');
			lst=a[i];
			--k;
		} else {
			ans.push_back('B');
			lst=b[i];
		}
	}
	reverse(ans.begin(), ans.end());
	cout << ans << '\n';
}

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