Codeforces Round 797 (Div. 3) |
---|
Finished |
You have a stripe of checkered paper of length $$$n$$$. Each cell is either white or black.
What is the minimum number of cells that must be recolored from white to black in order to have a segment of $$$k$$$ consecutive black cells on the stripe?
If the input data is such that a segment of $$$k$$$ consecutive black cells already exists, then print 0.
The first line contains an integer $$$t$$$ ($$$1 \le t \le 10^4$$$) — the number of test cases.
Next, descriptions of $$$t$$$ test cases follow.
The first line of the input contains two integers $$$n$$$ and $$$k$$$ ($$$1 \le k \le n \le 2\cdot10^5$$$). The second line consists of the letters 'W' (white) and 'B' (black). The line length is $$$n$$$.
It is guaranteed that the sum of values $$$n$$$ does not exceed $$$2\cdot10^5$$$.
For each of $$$t$$$ test cases print an integer — the minimum number of cells that need to be repainted from white to black in order to have a segment of $$$k$$$ consecutive black cells.
45 3BBWBW5 5BBWBW5 1BBWBW1 1W
1 2 0 1
In the first test case, $$$s$$$="BBWBW" and $$$k=3$$$. It is enough to recolor $$$s_3$$$ and get $$$s$$$="BBBBW". This string contains a segment of length $$$k=3$$$ consisting of the letters 'B'.
In the second test case of the example $$$s$$$="BBWBW" and $$$k=5$$$. It is enough to recolor $$$s_3$$$ and $$$s_5$$$ and get $$$s$$$="BBBBB". This string contains a segment of length $$$k=5$$$ consisting of the letters 'B'.
In the third test case of the example $$$s$$$="BBWBW" and $$$k=1$$$. The string $$$s$$$ already contains a segment of length $$$k=1$$$ consisting of the letters 'B'.
Name |
---|