Amazon Software Development Engineer I/II/II interview questions

I attended the amazon interview on 3rd Aug 2013 in Hyderabad. Written test for 1 hour but no limit on time given finally. 1) Given a single linked list of integers determine if it is palindrome. like 1 2 3 4 3 2 1. Need to support 1 2 3 3 4 3 3 1 as well. No extra allocation or space should be consumed.( can use some temp variable). 2) Given an array of integers A . Create one more arrary B fill each element (i th position) with the highest freq element from (0 to ith position in A array). 3) Given a series of number form a binary tree find the least the minimum weight binary tree. The weight of the node is depth x value of the element + weight of the left tree + weight of the right tree.Weight of the root node is the weight of the tree . Find the minimum weight binary tree out of all possible binary trees that are possible. And the code should return the minimum weight.