question about missing element in array

Question

i have following problem from book introduction algorithm second edition by MIT university

problem is following

An array A[1 . . n] contai

Answer 1

Here is a Python implementation:

def bit_at(n, bit):
    return (n>>bit) & 1

def find_missing(a, bits):

    indexes = range(len(a))
    missing = 0

    for bit in range(bits):

        ones = [i for i in indexes if bit_at(a[i], bit)==1]
        zeroes = [i for i in indexes if bit_at(a[i], bit)==0]

        if len(ones) <= len(zeroes):
            indexes = ones
            missing |= (1<