The time complexity is O(1).
Mid element of array is always repeated element.
Example : For even N.
N=4 Repeated element = N / 2 + 1 = 3
ARRAY 1,2,2,2
ARRAY 1 1 1 2
N=8 Repeated element = N / 2 + 1 = 5
ARRAY 1,2,2,4,4,4,4,4
ARRAY 1 2 2 2 2 2 4 5
ARRAY 2 2 2 2 2 3 4 5
Example : For Odd N.
N=3 Repeated element = N / 2 + 1 = 2
ARRAY 1,2,2,
ARRAY 1 1 2
N=7 Repeated element = N / 2 + 1 = 4
ARRAY 1,2,4,4,4,4, 5
ARRAY 2 2 2 2 3 4 5
ARRAY 2 3 3 3 3 4 5