Amazon Software Engineer Intern interview questions

Applied online and got an email from the recruiter in 4 5 days. Scheduled two 45 min phone interviews. was asked 2 programs for the first 45 min phone interview 1) deletion in circular linked list 2)Do division without using * ,/ ,% operators. For the second phone interview I was asked few questions on OOPS then was asked to write a code for the following question: 1) an array consists of few integers.Only 1 integer can be present for odd number of times.If any integer is present it has to be even number of times.Return error of this condition is violated.

One word: map. Know how to use it and its running times.