January 8, 2015 by Derek Illchuk Challenge: Constant-Time Min-Element Stack Here’s another problem from the Algorithm Design Manual (Skiena), Interview Problem 4-44: Design a stack that supports push, pop, and retrieving the minimum element in constant time. Can you do this? Hint 1Constant time? Well then it’s stacks all the way down. Hint 2Two stacks, to be exact. AnswerData structure contains two stacks, and . is the minimum element. After calling , push to if . Before calling , pop from if .