Problem Statement
You are given a string $S$ of length $N$ consisting of the characters A and B.
For a string $X$ of length $N$ consisting of the characters 1, 2, and 3, the score is determined by the following procedure:
First, initialize the variables
$h_1, h_2, h_3, P$to$0$.Then, for
$i = 1, 2, \dots, N$in this order, perform the following operations:
- If the
$i$-th character of$S$isA, perform operation A; if it isB, perform operation B. Let$d$be the number represented by the$i$-th character of$X$.- Operation A: Add
$2$to$h_d$.
- Operation B: If
$d = 2$or$h_d \neq h_2$, set$P$to$-10^{100}$. Otherwise, add$1$to both$h_d$and$h_2$.- If
$h_1 = h_2 = h_3$, add$1$to$P$.The final value of
$P$is the score.
Print one string $X$ that maximizes the score.
You have $T$ test cases to solve.
Constraints
$1 \leq T \leq 10^5$$1 \leq N \leq 10^6$$S$is a string of length$N$consisting ofAandB.$T$and$N$are integers.- The sum of
$N$across all test cases is at most$10^6$.
Input
The input is given from Standard Input in the following format. Here, $\mathrm{test}_i$ denotes the $i$-th test case.
T
\mathrm{test}_1
\mathrm{test}_2
\vdots
\mathrm{test}_T
Each test case is given in the following format:
N
S
Output
Print $T$ lines.
The $i$-th line $(1 \leq i \leq T)$ should contain a string $X$ that maximizes the score for the $i$-th test case.
If multiple strings $X$ maximize the score, any of them is considered correct.
样例
5
4
ABBA
5
AAAAA
6
BBBBBB
7
ABABABA
20
AAABBBBBBBBAAABBBABA
1333
12321
333333
1313212
33311111133121111311
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