#include <bits/stdc++.h>
using namespace std;
#define MAXN 500005
int n;
int arr[2*MAXN], brr[2*MAXN];
array<int, 2> dp[2*MAXN][2]; //a = 0, b = 1
vector<char> ans;
array<int, 2> comb(array<int, 2> a, array<int, 2> b){
if(a[0] == -1) return b;
if(b[0] == -1) return a;
return {min(a[0], b[0]), max(a[1], b[1])};
}
array<int, 2> add1(array<int, 2> a){
if(a[0] == -1) return a;
return {a[0]+1, a[1]+1};
}
bool contain(array<int, 2> a, int val){
return val >= a[0] && a[1] >= val;
}
void trace(int i, int j, int val){
if(i == 0){
if(j == 0) ans.push_back('A');
else ans.push_back('B');
return;
}
if(j == 0){
if(arr[i] >= arr[i-1]){
if(contain(dp[i-1][0], val)){
ans.push_back('A');
trace(i-1, 0, val);
return;
}
}
if(arr[i] >= brr[i-1]){
if(contain(dp[i-1][1], val)){
ans.push_back('A');
trace(i-1, 1, val);
return;
}
}
}
else{
if(brr[i] >= arr[i-1]){
if(contain(add1(dp[i-1][0]), val)){
ans.push_back('B');
trace(i-1, 0, val-1);
return;
}
}
if(brr[i] >= brr[i-1]){
if(contain(add1(dp[i-1][1]), val)){
ans.push_back('B');
trace(i-1, 1, val-1);
return;
}
}
}
}
int main(){
// freopen("a.in", "r", stdin);
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> n;
for(int i = 0; i<2*n; i++) cin >> arr[i];
for(int i = 0; i<2*n; i++) cin >> brr[i];
for(int i = 0; i<2*n; i++) dp[i][0] = dp[i][1] = {-1, -1};
dp[0][0] = {0, 0};
dp[0][1] = {1, 1};
for(int i = 1; i<2*n; i++){
if(arr[i] >= arr[i-1]) dp[i][0] = comb(dp[i][0], dp[i-1][0]);
if(arr[i] >= brr[i-1]) dp[i][0] = comb(dp[i][0], dp[i-1][1]);
if(brr[i] >= arr[i-1]) dp[i][1] = comb(dp[i][1], add1(dp[i-1][0]));
if(brr[i] >= brr[i-1]) dp[i][1] = comb(dp[i][1], add1(dp[i-1][1]));
}
if(!(contain(dp[2*n-1][0], n) || contain(dp[2*n-1][1], n))){
cout << -1 << endl;
return 0;
}
if(contain(dp[2*n-1][0], n)) trace(2*n-1, 0, n);
else trace(2*n-1, 1, n);
reverse(ans.begin(), ans.end());
for(auto x : ans) cout << x;
cout << endl;
}
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
364 KB |
Output is correct |
2 |
Correct |
1 ms |
364 KB |
Output is correct |
3 |
Correct |
1 ms |
364 KB |
Output is correct |
4 |
Correct |
1 ms |
364 KB |
Output is correct |
5 |
Correct |
2 ms |
512 KB |
Output is correct |
6 |
Correct |
2 ms |
748 KB |
Output is correct |
7 |
Correct |
2 ms |
640 KB |
Output is correct |
8 |
Correct |
2 ms |
748 KB |
Output is correct |
9 |
Correct |
2 ms |
620 KB |
Output is correct |
10 |
Correct |
2 ms |
620 KB |
Output is correct |
11 |
Correct |
2 ms |
748 KB |
Output is correct |
12 |
Correct |
3 ms |
748 KB |
Output is correct |
13 |
Correct |
3 ms |
748 KB |
Output is correct |
14 |
Correct |
2 ms |
748 KB |
Output is correct |
15 |
Correct |
2 ms |
748 KB |
Output is correct |
16 |
Correct |
2 ms |
492 KB |
Output is correct |
17 |
Correct |
2 ms |
748 KB |
Output is correct |
18 |
Correct |
3 ms |
748 KB |
Output is correct |
19 |
Correct |
3 ms |
748 KB |
Output is correct |
20 |
Correct |
2 ms |
620 KB |
Output is correct |
21 |
Correct |
2 ms |
748 KB |
Output is correct |
22 |
Correct |
2 ms |
620 KB |
Output is correct |
23 |
Correct |
2 ms |
620 KB |
Output is correct |
24 |
Correct |
3 ms |
876 KB |
Output is correct |
25 |
Correct |
2 ms |
620 KB |
Output is correct |
26 |
Correct |
2 ms |
748 KB |
Output is correct |
27 |
Correct |
2 ms |
748 KB |
Output is correct |
28 |
Correct |
2 ms |
620 KB |
Output is correct |
29 |
Correct |
2 ms |
748 KB |
Output is correct |
30 |
Correct |
2 ms |
640 KB |
Output is correct |
31 |
Correct |
2 ms |
748 KB |
Output is correct |
32 |
Correct |
2 ms |
764 KB |
Output is correct |
33 |
Correct |
2 ms |
748 KB |
Output is correct |
# |
Verdict |
Execution time |
Memory |
Grader output |
1 |
Correct |
1 ms |
364 KB |
Output is correct |
2 |
Correct |
1 ms |
364 KB |
Output is correct |
3 |
Correct |
1 ms |
364 KB |
Output is correct |
4 |
Correct |
1 ms |
364 KB |
Output is correct |
5 |
Correct |
2 ms |
512 KB |
Output is correct |
6 |
Correct |
2 ms |
748 KB |
Output is correct |
7 |
Correct |
2 ms |
640 KB |
Output is correct |
8 |
Correct |
2 ms |
748 KB |
Output is correct |
9 |
Correct |
2 ms |
620 KB |
Output is correct |
10 |
Correct |
2 ms |
620 KB |
Output is correct |
11 |
Correct |
2 ms |
748 KB |
Output is correct |
12 |
Correct |
3 ms |
748 KB |
Output is correct |
13 |
Correct |
3 ms |
748 KB |
Output is correct |
14 |
Correct |
2 ms |
748 KB |
Output is correct |
15 |
Correct |
2 ms |
748 KB |
Output is correct |
16 |
Correct |
2 ms |
492 KB |
Output is correct |
17 |
Correct |
2 ms |
748 KB |
Output is correct |
18 |
Correct |
3 ms |
748 KB |
Output is correct |
19 |
Correct |
3 ms |
748 KB |
Output is correct |
20 |
Correct |
2 ms |
620 KB |
Output is correct |
21 |
Correct |
2 ms |
748 KB |
Output is correct |
22 |
Correct |
2 ms |
620 KB |
Output is correct |
23 |
Correct |
2 ms |
620 KB |
Output is correct |
24 |
Correct |
3 ms |
876 KB |
Output is correct |
25 |
Correct |
2 ms |
620 KB |
Output is correct |
26 |
Correct |
2 ms |
748 KB |
Output is correct |
27 |
Correct |
2 ms |
748 KB |
Output is correct |
28 |
Correct |
2 ms |
620 KB |
Output is correct |
29 |
Correct |
2 ms |
748 KB |
Output is correct |
30 |
Correct |
2 ms |
640 KB |
Output is correct |
31 |
Correct |
2 ms |
748 KB |
Output is correct |
32 |
Correct |
2 ms |
764 KB |
Output is correct |
33 |
Correct |
2 ms |
748 KB |
Output is correct |
34 |
Correct |
250 ms |
23532 KB |
Output is correct |
35 |
Correct |
318 ms |
67688 KB |
Output is correct |
36 |
Correct |
308 ms |
66792 KB |
Output is correct |
37 |
Correct |
320 ms |
68072 KB |
Output is correct |
38 |
Correct |
305 ms |
68072 KB |
Output is correct |
39 |
Correct |
303 ms |
68456 KB |
Output is correct |
40 |
Correct |
328 ms |
72604 KB |
Output is correct |
41 |
Correct |
305 ms |
69352 KB |
Output is correct |
42 |
Correct |
328 ms |
70760 KB |
Output is correct |
43 |
Correct |
343 ms |
72936 KB |
Output is correct |
44 |
Correct |
348 ms |
73024 KB |
Output is correct |
45 |
Correct |
343 ms |
72936 KB |
Output is correct |
46 |
Correct |
325 ms |
72936 KB |
Output is correct |
47 |
Correct |
333 ms |
73036 KB |
Output is correct |
48 |
Correct |
323 ms |
72936 KB |
Output is correct |
49 |
Correct |
321 ms |
72936 KB |
Output is correct |
50 |
Correct |
335 ms |
72936 KB |
Output is correct |
51 |
Correct |
335 ms |
73064 KB |
Output is correct |
52 |
Correct |
263 ms |
74472 KB |
Output is correct |
53 |
Correct |
263 ms |
74344 KB |
Output is correct |
54 |
Correct |
249 ms |
74348 KB |
Output is correct |
55 |
Correct |
247 ms |
74344 KB |
Output is correct |
56 |
Correct |
326 ms |
72936 KB |
Output is correct |
57 |
Correct |
289 ms |
73960 KB |
Output is correct |
58 |
Correct |
289 ms |
74216 KB |
Output is correct |
59 |
Correct |
287 ms |
74344 KB |
Output is correct |
60 |
Correct |
271 ms |
69864 KB |
Output is correct |
61 |
Correct |
295 ms |
74344 KB |
Output is correct |
62 |
Correct |
288 ms |
73192 KB |
Output is correct |
63 |
Correct |
296 ms |
74344 KB |
Output is correct |
64 |
Correct |
281 ms |
71784 KB |
Output is correct |
65 |
Correct |
293 ms |
74216 KB |
Output is correct |