[Comment] Array out of bound when looking for middle point
[Improvement] Compare array's half length with k/2. Choose smaller one
[Failed] ArrayIndexOutOfBoundsException: [], [2,3]

— len1 - 1 = -1, A[-1] out of bound
Revert "[Failed] ArrayIndexOutOfBoundsException: [], [2,3]"

This reverts commit 6440df15b2cdeca16fdd1c83646a407e6012ec27.
[Failed] If array size equals 0, then indexing will be out of bound:[], [1]
[Improvement] Move if(k==0) after index check, so that 0 size can be dealt first
[Failed] len1 - 1 out of bound for 0 size arrays
[Improvement] Added || condition to deal with size of 0
[Failed] [1], [1]: A[1] out of bound
[Failed] No idea what's solution yet