Amazon Software Engineer interview questions

2 phone Interviews and 1 face to face interview. Interview questions. What is recall is this Quickest way to find missing number and missing slot in array of 100 elements Iterate through the array and compute the sum of all numbers. Now, sum of natural numbers from 1 to N, can be expressed as Nx(N+1)/2. N=100. Subtract the sum of the array from Nx(N+1)/2, where N=100. That is the missing number. The empty slot can be detected during the iteration in which the sum is computed. // will be the sum of the numbers in the array. int sum = 0; int idx = -1; for (int i = 0; i < arr.length; i++) { if (arr[i] == 0) { idx = i; } else { sum += arr[i]; } } // the total sum of numbers between 1 and arr.length. int total = (arr.length + 1) * arr.length / 2; System.out.println("missing number is: " + (total - sum) + " at index " + idx);

They picked my resume from monster.com. I got a mail to schedule a phone interview and they asked me to apply for software development position on their website. The interview was purely technical. The interviewer asked mostly data structures and algorithms questions; binary search tree, linked lists, complexities of some known algorithms etc. There was one coding question. The interviewer asked to explain how I would go about solving the problem and then gave 1 hour to code and mail it.