Microsoft Interview Question

home assignment: 1. find whats wrong with the code (if statment with =) 2. return largest letter from a string, which occurs twice, once as a small letter and one as a big letter. ('AaBabc' should return B) 3. a matrix of strings that represent a checkers board, return the maximum steps white can do online interviews: 1. Maximum number of overlapping Intervals (need to do it in o(nlogn) time ) 2. Check for Balanced Brackets in an expression (using Stack) 3. figure out a way to flatten a binary tree to a file, then read it in a different app, and write the method to reconstruct the tree. 4. how would you have implemented a calculator (need to use some kind of composite pattern, with a stack to hold some math logic and IOperator)