CF1669D.Colorful Stamp

传统题 时间 2000 ms 内存 256 MiB 5 尝试 1 已通过 1 标签

Colorful Stamp

A row of nn cells is given, all initially white. Using a stamp, you can stamp any two neighboring cells such that one becomes red and the other becomes blue. A stamp can be rotated, i.e. it can be used in both ways: as BR\color{blue}{\texttt{B}}\color{red}{\texttt{R}} and as RB\color{red}{\texttt{R}}\color{blue}{\texttt{B}}.

During use, the stamp must completely fit on the given nn cells (it cannot be partially outside the cells). The stamp can be applied multiple times to the same cell. Each usage of the stamp recolors both cells that are under the stamp.

For example, one possible sequence of stamps to make the picture $\color{blue}{\texttt{B}}\color{red}{\texttt{R}}\color{blue}{\texttt{B}}\color{blue}{\texttt{B}}\texttt{W}$ could be WWWWW} \to \texttt{WW}\color{brown}{\underline{\color{red}{\texttt{R}}\color{blue}{\texttt{B}}}}\texttt{W} \to \color{brown}{\underline{\color{blue}{\texttt{B}}\color{red}{\texttt{R}}}}\color{red}{\texttt{R}}\color{blue}{\texttt{B}}\texttt{W} \to \color{blue}{\texttt{B}}\color{brown}{\underline{\color{red}{\texttt{R}}\color{blue}{\texttt{B}}}}\color{blue}{\texttt{B}}\texttt{W. Here W, R\color{red}{\texttt{R}}, and B\color{blue}{\texttt{B}} represent a white, red, or blue cell, respectively, and the cells that the stamp is used on are marked with an underline.

Given a final picture, is it possible to make it using the stamp zero or more times?

Input

The first line contains an integer tt (1t1041 \leq t \leq 10^4) — the number of test cases.

The first line of each test case contains an integer nn (1n1051 \leq n \leq 10^5) — the length of the picture.

The second line of each test case contains a string ss — the picture you need to make. It is guaranteed that the length of ss is nn and that ss only consists of the characters W, R, and B, representing a white, red, or blue cell, respectively.

It is guaranteed that the sum of nn over all test cases does not exceed 10510^5.

Output

Output tt lines, each of which contains the answer to the corresponding test case. As an answer, output "YES" if it possible to make the picture using the stamp zero or more times, and "NO" otherwise.

You can output the answer in any case (for example, the strings "yEs", "yes", "Yes" and "YES" will be recognized as a positive answer).

Note

The first test case is explained in the statement.

For the second, third, and fourth test cases, it is not possible to stamp a single cell, so the answer is "NO".

For the fifth test case, you can use the stamp as follows: WWW} \to \texttt{W}\color{brown}{\underline{\color{red}{\texttt{R}}\color{blue}{\texttt{B}}}} \to \color{brown}{\underline{\color{blue}{\texttt{B}}\color{red}{\texttt{R}}}}\color{blue}{\texttt{B}.

For the sixth test case, you can use the stamp as follows: WWW} \to \texttt{W}\color{brown}{\underline{\color{red}{\texttt{R}}\color{blue}{\texttt{B}}}} \to \color{brown}{\underline{\color{red}{\texttt{R}}\color{blue}{\texttt{B}}}}\color{blue}{\texttt{B}.

For the seventh test case, you don't need to use the stamp at all.

Samples

12
5
BRBBW
1
B
2
WB
2
RW
3
BRB
3
RBB
7
WWWWWWW
9
RBWBWRRBW
10
BRBRBRBRRB
12
BBBRWWRRRWBR
10
BRBRBRBRBW
5
RBWBW
YES
NO
NO
NO
YES
YES
YES
NO
YES
NO
YES
NO

在线编程 IDE

建议全屏模式获得最佳体验