CF1873D.1D Eraser

You are given a strip of paper $s$ that is $n$ cells long. Each cell is either black or white. In an operation you can take any $k$ consecutive cells and make them all white.

Find the minimum number of operations needed to remove all black cells.

你有一条长度为 $n$ 的纸带 $s$。每个格子要么是黑色，要么是白色。每次操作中，你可以任选连续的 $k$ 个格子，并将它们全部变为白色。

求清除所有黑色格子所需的最少操作次数。

The first line contains a single integer $t$ ($1 \leq t \leq 1000$) — the number of test cases.

The first line of each test case contains two integers $n$ and $k$ ($1 \leq k \leq n \leq 2 \cdot 10^5$) — the length of the paper and the integer used in the operation.

The second line of each test case contains a string $s$ of length $n$ consisting of characters $\texttt{B}$ (representing a black cell) or $\texttt{W}$ (representing a white cell).

The sum of $n$ over all test cases does not exceed $2 \cdot 10^5$.

第一行包含一个整数 $t$（$1 \leq t \leq 1000$）—— 测试用例的数量。

每个测试用例的第一行包含两个整数 $n$ 和 $k$（$1 \leq k \leq n \leq 2 \cdot 10^5$）—— 纸张的长度以及操作中使用的整数。

每个测试用例的第二行包含一个长度为 $n$ 的字符串 $s$，由字符 $\texttt{B}$（表示黑色格子）或 $\texttt{W}$（表示白色格子）组成。

所有测试用例的 $n$ 之和不超过 $2 \cdot 10^5$。

For each test case, output a single integer — the minimum number of operations needed to remove all black cells.

对于每个测试用例，输出一个整数——移除所有黑格所需的最少操作次数。

In the first test case you can perform the following operations: $$\color{red}{\texttt{WBW}}\texttt{WWB} \to \texttt{WWW}\color{red}{\texttt{WWB}} \to \texttt{WWWWWW}$$

In the second test case you can perform the following operations: $$\texttt{WW}\color{red}{\texttt{BWB}}\texttt{WW} \to \texttt{WWWWWWW}$$

In the third test case you can perform the following operations: $$\texttt{B}\color{red}{\texttt{WBWB}} \to \color{red}{\texttt{BWWW}}\texttt{W} \to \texttt{WWWWW}$$

在第一个测试用例中，你可以执行以下操作：$$\color{red}{\texttt{WBW}}\texttt{WWB} \to \texttt{WWW}\color{red}{\texttt{WWB}} \to \texttt{WWWWWW}$$

在第二个测试用例中，你可以执行以下操作：$$\texttt{WW}\color{red}{\texttt{BWB}}\texttt{WW} \to \texttt{WWWWWWW}$$

在第三个测试用例中，你可以执行以下操作：$$\texttt{B}\color{red}{\texttt{WBWB}} \to \color{red}{\texttt{BWWW}}\texttt{W} \to \texttt{WWWWW}$$