maxMirror challenge

Hi,

I am working on below challenge

http://codingbat.com/prob/p196409

Array-3 > maxMirror
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We'll say that a "mirror" section in an array is a group of contiguous elements such that somewhere in the array, the same group appears in reverse order. For example, the largest mirror section in {1, 2, 3, 8, 9, 3, 2, 1} is length 3 (the {1, 2, 3} part). Return the size of the largest mirror section found in the given array.

maxMirror([1, 2, 3, 8, 9, 3, 2, 1]) → 3
maxMirror([1, 2, 1, 4]) → 3
maxMirror([7, 1, 2, 9, 7, 2, 1]) → 2

i have not completely understood the description.

How below is 3

maxMirror([1, 2, 1, 4]) → 3