Submission #335301

#	Time	Username	Problem	Language	Result	Execution time	Memory
335301		alishahali1382	Building 4 (JOI20_building4)	C++14	100 / 100	263 ms	28384 KiB

building4

#include <bits/stdc++.h>
#pragma GCC optimize ("O2,unroll-loops")
//#pragma GCC optimize("no-stack-protector,fast-math")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")

using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<pii, int> piii;
typedef pair<ll, ll> pll;
#define debug(x) cerr<<#x<<'='<<(x)<<endl;
#define debugp(x) cerr<<#x<<"= {"<<(x.first)<<", "<<(x.second)<<"}"<<endl;
#define debug2(x, y) cerr<<"{"<<#x<<", "<<#y<<"} = {"<<(x)<<", "<<(y)<<"}"<<endl;
#define debugv(v) {cerr<<#v<<" : ";for (auto x:v) cerr<<x<<' ';cerr<<endl;}
#define all(x) x.begin(), x.end()
#define pb push_back
#define kill(x) return cout<<x<<'\n', 0;

const int inf=1000000010;
const ll INF=10000000000000010LL;
const int mod=1000000007;
const int MAXN=1000010, LOG=20;

int n, m, k, u, v, x, y, t, a, b;
int A[MAXN], B[MAXN];
int dp[2][MAXN][2];
string ans;

int main(){
	ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);
	cin>>n;
	for (int i=1; i<=2*n; i++) cin>>A[i];
	for (int i=1; i<=2*n; i++) cin>>B[i];
	for (int i=1; i<=2*n; i++){
		dp[0][i][0]=dp[1][i][0]=inf;
		dp[0][i][1]=dp[1][i][1]=-inf;
		if (A[i-1]<=A[i]){
			dp[0][i][0]=min(dp[0][i][0], dp[0][i-1][0]+1);
			dp[0][i][1]=max(dp[0][i][1], dp[0][i-1][1]+1);
		}
		if (A[i-1]<=B[i]){
			dp[1][i][0]=min(dp[1][i][0], dp[0][i-1][0]);
			dp[1][i][1]=max(dp[1][i][1], dp[0][i-1][1]);
		}
		if (B[i-1]<=A[i]){
			dp[0][i][0]=min(dp[0][i][0], dp[1][i-1][0]+1);
			dp[0][i][1]=max(dp[0][i][1], dp[1][i-1][1]+1);
		}
		if (B[i-1]<=B[i]){
			dp[1][i][0]=min(dp[1][i][0], dp[1][i-1][0]);
			dp[1][i][1]=max(dp[1][i][1], dp[1][i-1][1]);
		}
	}
	int last=-1;
	if (dp[0][2*n][0]<=n && n<=dp[0][2*n][1]) last=0;
	if (dp[1][2*n][0]<=n && n<=dp[1][2*n][1]) last=1;
	if (last==-1) kill(-1)
	k=n;
	for (int i=2*n; i; i--){
		if (!last) k--;
		ans+='A'+last;
		bool okA=(last==0 && A[i-1]<=A[i] || last==1 && A[i-1]<=B[i]);
		bool okB=(last==0 && B[i-1]<=A[i] || last==1 && B[i-1]<=B[i]);
		if (okA && dp[0][i-1][0]<=k && k<=dp[0][i-1][1]) last=0;
		if (okB && dp[1][i-1][0]<=k && k<=dp[1][i-1][1]) last=1;
	}
	reverse(all(ans));
	cout<<ans<<"\n";
	
	return 0;
}
/*
3
2 5 4 9 15 11
6 7 6 8 12 14

2
1 4 10 20
3 5 8 13

2
3 4 5 6
10 9 8 7

6
25 18 40 37 29 95 41 53 39 69 61 90
14 18 22 28 18 30 32 32 63 58 71 78

*/

Compilation message (stderr)

building4.cpp: In function 'int main()':
building4.cpp:65:21: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   65 |   bool okA=(last==0 && A[i-1]<=A[i] || last==1 && A[i-1]<=B[i]);
      |             ~~~~~~~~^~~~~~~~~~~~~~~
building4.cpp:66:21: warning: suggest parentheses around '&&' within '||' [-Wparentheses]
   66 |   bool okB=(last==0 && B[i-1]<=A[i] || last==1 && B[i-1]<=B[i]);
      |             ~~~~~~~~^~~~~~~~~~~~~~~

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