CF1800B.Count the Number of Pairs
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题目描述
Kristina has a string s of length n , consisting only of lowercase and uppercase Latin letters. For each pair of lowercase letter and its matching uppercase letter, Kristina can get 1 burl. However, pairs of characters cannot overlap, so each character can only be in one pair.
For example, if she has the string s = "aAaaBACacbE", she can get a burl for the following character pairs:
- s1 = "a" and s2 = "A"
- s4 = "a" and s6 = "A"
- s5 = "B" and s10 = "b"
- s7 = "C" and s9 = "c"
Kristina wants to get more burles for her string, so she is going to perform no more than k operations on it. In one operation, she can:
- either select the lowercase character si ( 1≤i≤n ) and make it uppercase.
- or select uppercase character si ( 1≤i≤n ) and make it lowercase.
For example, when k = 2 and s = "aAaaBACacbE" it can perform one operation: choose s3 = "a" and make it uppercase. Then she will get another pair of s3 = "A" and s8 = "a"
Find maximum number of burles Kristina can get for her string.
输入格式
The first line of input data contains a single integer t ( 1≤t≤104 ) — the number of test cases.
The description of the test cases follows.
The first line of each test case contains two integers n ( 1≤n≤2⋅105 ) and k ( 0≤k≤n ) — the number of characters in the string and the maximum number of operations that can be performed on it.
The second line of each test case contains a string s of length n , consisting only of lowercase and uppercase Latin letters.
It is guaranteed that the sum of n over all test cases does not exceed 2⋅105 .
输出格式
For each test case, print exactly one integer on a separate line: the maximum number of burles that Kristina can get for her string s .
输入输出样例
输入#1
5 11 2 aAaaBACacbE 2 2 ab 4 1 aaBB 6 0 abBAcC 5 3 cbccb
输出#1
5 0 1 3 2
说明/提示
The first test case is explained in the problem statement.
In the second test case, it is not possible to get any pair by performing any number of operations.