CS 2401, Spring 2009 Typical mistakes for Test 2 Problem 1: Problem 2: * the input should be a string, an algorithm should use stacks * the algorithm was described in the class: if you see [ you push; if you see ], you pop * it is not always possible to pop; if the stack is empty, you cannot pop; example is a string "]" * a character and a string are completely different data types * the problem asks for a method, so it should be a method Problem 3: * a code stack.pop() is not a code for popping an element in an array implementation Problem 5: * elements are not moved when an element is dequeued, what is changed are the indices "first" and "last" ("front" and "rear") Problem 6: * according to the book, ADT is a way to implement operations on the logical level, independent on how different objects are operations are implemented; since most students seem to be confused on this, I added 2 points to all the answers, making 10/10 an average grade on this question