Indeed Software Engineer interview questions

Applied for position in Tokyo. The process starts with a online programming test on a japanese site that runs programming contests called atcoder.jp. The times available to take the test are a little bit convenient. The test consists of 4 questions. Your choice of programming language. The questions starts easy and get more difficult as you proceed.

Online test and asked me for a phone interview two day later. Phone interview is actually quite easy, find the first duplicated word in a string. like "sky blue dark blue", simply return blue. Just use a hashset and it is solved! I wrote the code in one shot and then he asked about some of the basic problems of hashtable, time complexity etc, which I was able to answer very quickly. Then he asked if the string is so big, that it is a book, how would you do that? A little bit communication with the interviewer and I was able to give the solution as well. But go rejection email three days later. And I have no idea why.