#include <bits/stdc++.h>
using namespace std;
#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define MOD 1000000007
typedef long long ll;
typedef pair <int, int> ii;
typedef pair <ll, ll> pll;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef long double ld;
ll INF=LLONG_MAX;
int const mxn = 1e6+5;
int dp[mxn][2][2]; //pos, cur, min/max = cnt of b;
int a[mxn],b[mxn];
void mins(int &a, int b){
a = min(a,b);
return;
}
void maxs(int &a, int b){
a = max(a,b);
return;
}
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0);
//freopen("input.txt","r",stdin); freopen("output.txt","w",stdout);
int n; cin >> n;
for(int i=1; i<=n*2; i++)cin >> a[i];
for(int i=1; i<=n*2; i++)cin >> b[i];
dp[1][0][0] = dp[1][0][1] = 0;
dp[1][1][0] = dp[1][1][1] = 1;
for(int i=2; i<=n*2; i++){
dp[i][0][0]=dp[i][1][0] = mxn;
dp[i][0][1]=dp[i][1][1] = -1;
if(a[i]>=a[i-1]){
mins(dp[i][0][0],dp[i-1][0][0]);
maxs(dp[i][0][1],dp[i-1][0][1]);
}
if(a[i]>=b[i-1]){
mins(dp[i][0][0],dp[i-1][1][0]);
maxs(dp[i][0][1],dp[i-1][1][1]);
}
if(b[i]>=a[i-1]){
mins(dp[i][1][0],dp[i-1][0][0]+1);
maxs(dp[i][1][1],dp[i-1][0][1]+1);
}
if(b[i]>=b[i-1]){
mins(dp[i][1][0],dp[i-1][1][0]+1);
maxs(dp[i][1][1],dp[i-1][1][1]+1);
}
}
bool cur=0; int cnt=n;
if(dp[n*2][0][0]<=n&&n<=dp[n*2][0][1])cur = 0;
else if(dp[n*2][1][0]<=n&&n<=dp[n*2][1][1])cur = 1;
else{
cout << -1 << endl;
return 0;
}
//start backtracking
string s="";
for(int i=n*2; i>=1; i--){
if(!cur){
s+='A';
if(a[i-1]<=a[i]&&dp[i-1][0][0]<=cnt&&cnt<=dp[i-1][0][1])cur = 0;
if(b[i-1]<=a[i]&&dp[i-1][1][0]<=cnt&&cnt<=dp[i-1][1][1])cur = 1;
}else{
s+='B';
cnt--;
if(a[i-1]<=b[i]&&dp[i-1][0][0]<=cnt&&cnt<=dp[i-1][0][1])cur = 0;
if(b[i-1]<=b[i]&&dp[i-1][1][0]<=cnt&&cnt<=dp[i-1][1][1])cur = 1;
}
}
reverse(all(s));
cout << s << endl;
}
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
5 ms |
384 KB |
Output is correct |
| 2 |
Correct |
4 ms |
384 KB |
Output is correct |
| 3 |
Correct |
4 ms |
384 KB |
Output is correct |
| 4 |
Correct |
5 ms |
512 KB |
Output is correct |
| 5 |
Correct |
6 ms |
512 KB |
Output is correct |
| 6 |
Correct |
6 ms |
512 KB |
Output is correct |
| 7 |
Correct |
6 ms |
512 KB |
Output is correct |
| 8 |
Correct |
6 ms |
512 KB |
Output is correct |
| 9 |
Correct |
6 ms |
512 KB |
Output is correct |
| 10 |
Correct |
5 ms |
512 KB |
Output is correct |
| 11 |
Correct |
6 ms |
512 KB |
Output is correct |
| 12 |
Correct |
6 ms |
512 KB |
Output is correct |
| 13 |
Correct |
6 ms |
512 KB |
Output is correct |
| 14 |
Correct |
6 ms |
512 KB |
Output is correct |
| 15 |
Correct |
6 ms |
512 KB |
Output is correct |
| 16 |
Correct |
6 ms |
512 KB |
Output is correct |
| 17 |
Correct |
6 ms |
512 KB |
Output is correct |
| 18 |
Correct |
6 ms |
512 KB |
Output is correct |
| 19 |
Correct |
6 ms |
512 KB |
Output is correct |
| 20 |
Correct |
5 ms |
512 KB |
Output is correct |
| 21 |
Correct |
5 ms |
512 KB |
Output is correct |
| 22 |
Correct |
5 ms |
512 KB |
Output is correct |
| 23 |
Correct |
5 ms |
512 KB |
Output is correct |
| 24 |
Correct |
6 ms |
512 KB |
Output is correct |
| 25 |
Correct |
6 ms |
512 KB |
Output is correct |
| 26 |
Correct |
5 ms |
512 KB |
Output is correct |
| 27 |
Correct |
5 ms |
512 KB |
Output is correct |
| 28 |
Correct |
5 ms |
512 KB |
Output is correct |
| 29 |
Correct |
5 ms |
512 KB |
Output is correct |
| 30 |
Correct |
5 ms |
512 KB |
Output is correct |
| 31 |
Correct |
6 ms |
512 KB |
Output is correct |
| 32 |
Correct |
5 ms |
512 KB |
Output is correct |
| 33 |
Correct |
5 ms |
512 KB |
Output is correct |
| # |
Verdict |
Execution time |
Memory |
Grader output |
| 1 |
Correct |
5 ms |
384 KB |
Output is correct |
| 2 |
Correct |
4 ms |
384 KB |
Output is correct |
| 3 |
Correct |
4 ms |
384 KB |
Output is correct |
| 4 |
Correct |
5 ms |
512 KB |
Output is correct |
| 5 |
Correct |
6 ms |
512 KB |
Output is correct |
| 6 |
Correct |
6 ms |
512 KB |
Output is correct |
| 7 |
Correct |
6 ms |
512 KB |
Output is correct |
| 8 |
Correct |
6 ms |
512 KB |
Output is correct |
| 9 |
Correct |
6 ms |
512 KB |
Output is correct |
| 10 |
Correct |
5 ms |
512 KB |
Output is correct |
| 11 |
Correct |
6 ms |
512 KB |
Output is correct |
| 12 |
Correct |
6 ms |
512 KB |
Output is correct |
| 13 |
Correct |
6 ms |
512 KB |
Output is correct |
| 14 |
Correct |
6 ms |
512 KB |
Output is correct |
| 15 |
Correct |
6 ms |
512 KB |
Output is correct |
| 16 |
Correct |
6 ms |
512 KB |
Output is correct |
| 17 |
Correct |
6 ms |
512 KB |
Output is correct |
| 18 |
Correct |
6 ms |
512 KB |
Output is correct |
| 19 |
Correct |
6 ms |
512 KB |
Output is correct |
| 20 |
Correct |
5 ms |
512 KB |
Output is correct |
| 21 |
Correct |
5 ms |
512 KB |
Output is correct |
| 22 |
Correct |
5 ms |
512 KB |
Output is correct |
| 23 |
Correct |
5 ms |
512 KB |
Output is correct |
| 24 |
Correct |
6 ms |
512 KB |
Output is correct |
| 25 |
Correct |
6 ms |
512 KB |
Output is correct |
| 26 |
Correct |
5 ms |
512 KB |
Output is correct |
| 27 |
Correct |
5 ms |
512 KB |
Output is correct |
| 28 |
Correct |
5 ms |
512 KB |
Output is correct |
| 29 |
Correct |
5 ms |
512 KB |
Output is correct |
| 30 |
Correct |
5 ms |
512 KB |
Output is correct |
| 31 |
Correct |
6 ms |
512 KB |
Output is correct |
| 32 |
Correct |
5 ms |
512 KB |
Output is correct |
| 33 |
Correct |
5 ms |
512 KB |
Output is correct |
| 34 |
Correct |
290 ms |
24288 KB |
Output is correct |
| 35 |
Correct |
293 ms |
24240 KB |
Output is correct |
| 36 |
Correct |
292 ms |
23856 KB |
Output is correct |
| 37 |
Correct |
292 ms |
24240 KB |
Output is correct |
| 38 |
Correct |
285 ms |
24412 KB |
Output is correct |
| 39 |
Correct |
264 ms |
24368 KB |
Output is correct |
| 40 |
Correct |
289 ms |
25836 KB |
Output is correct |
| 41 |
Correct |
281 ms |
24752 KB |
Output is correct |
| 42 |
Correct |
298 ms |
25264 KB |
Output is correct |
| 43 |
Correct |
309 ms |
28780 KB |
Output is correct |
| 44 |
Correct |
312 ms |
28908 KB |
Output is correct |
| 45 |
Correct |
312 ms |
28908 KB |
Output is correct |
| 46 |
Correct |
298 ms |
29036 KB |
Output is correct |
| 47 |
Correct |
297 ms |
26156 KB |
Output is correct |
| 48 |
Correct |
289 ms |
26092 KB |
Output is correct |
| 49 |
Correct |
300 ms |
27500 KB |
Output is correct |
| 50 |
Correct |
293 ms |
25964 KB |
Output is correct |
| 51 |
Correct |
300 ms |
25964 KB |
Output is correct |
| 52 |
Correct |
184 ms |
27116 KB |
Output is correct |
| 53 |
Correct |
186 ms |
27120 KB |
Output is correct |
| 54 |
Correct |
170 ms |
27116 KB |
Output is correct |
| 55 |
Correct |
173 ms |
26988 KB |
Output is correct |
| 56 |
Correct |
315 ms |
28140 KB |
Output is correct |
| 57 |
Correct |
250 ms |
26860 KB |
Output is correct |
| 58 |
Correct |
345 ms |
26988 KB |
Output is correct |
| 59 |
Correct |
259 ms |
26732 KB |
Output is correct |
| 60 |
Correct |
245 ms |
25256 KB |
Output is correct |
| 61 |
Correct |
245 ms |
26860 KB |
Output is correct |
| 62 |
Correct |
254 ms |
26348 KB |
Output is correct |
| 63 |
Correct |
249 ms |
26732 KB |
Output is correct |
| 64 |
Correct |
242 ms |
25904 KB |
Output is correct |
| 65 |
Correct |
261 ms |
26604 KB |
Output is correct |
