Two Sum Existence

You are given an array of integers and an integer target k. Your task is to determine whether there exist two different indices i and j in the array such that the following equation holds:

\(arr[i] + arr[j] = k\)

If such a pair exists, print YES; otherwise, print NO. The answer for each test case should be output on a separate line in the format Case i: YES or Case i: NO, where i is the test case number (starting from 1).

This problem tests your ability to efficiently search for pairs in arrays using techniques such as hashing.

inputFormat

The input begins with an integer T on the first line, representing the number of test cases.

Each test case is described as follows:

• The first line of each test case contains two integers n and k, where n is the number of elements in the array, and k is the target sum.
• The second line contains n space-separated integers representing the array elements.

outputFormat

For each test case, output a single line in the following format:

Case i: YES or Case i: NO

Here, i is the test case number (starting from 1), and the answer is YES if there exist two distinct indices such that arr[i] + arr[j] = k (where i ≠ j), and NO otherwise.

## sample

3
4 9
2 7 11 15
3 10
1 5 3
5 7
1 2 3 4 5

Case 1: YES
Case 2: NO
Case 3: YES

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