Amazon Intern interview questions

Totally four rounds 1.Online apti with two programs(1.30hr) 2.Technical interview(45mins) 3.Technical interview(45mins) 4.HR(30mins) In first round 20 technical apti in ds and c and two programs. First i did the programs because only programs are impart. I done one program.And i selected for next round. In 2nd technical round they asked two programs. One is finding Kth largest element in BST. and another one is finding Kth largest element in given no of sorted arrays. I write a program for first one. And told logic for second one. But i didn't selected for next round.