Smallest OR Neighbor

Easy

You get a list of primes primes. For each p, find the smallest non-negative integer a such that the bitwise OR of a and a + 1 equals p: a | (a + 1) == p If no such a exists, use -1. Return the answers in the same order as the numbers in primes.

Example 1

primes=[5, 19] → [4, 17]

4 OR 5 = 5, and nothing smaller works. For 19 (10011) the answer is 17 (10001): 17 OR 18 = 19.

Example 2

primes=[2, 3] → [-1, 1]

a OR (a + 1) is always odd, so 2 has no answer: -1. For 3 it is 1, since 1 OR 2 = 3.

Example 3

primes=[31, 23] → [15, 19]

Constraints

1 ≤ len(primes) ≤ 100
2 ≤ primes[i] ≤ 1000
Every primes[i] is prime

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Topics

Bit Manipulation Array

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Input

primes=[5, 19]

Expected

[4, 17]

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