O(1)

Problem Stack with find-min/find-max in O(1) time Solution Method 1 - using extra stacks for min and max The basic idea of the solution can be found here. Here instead of 2 stacks we will be using 3 stacks -1 stack with normal elements, 1 with only max elements and 1 with min element. Now the operations will be following : push: - If the element being pushed is less than the top element of ‘min_stack’ then push it on ‘min_stack’ as well. [Read More]

Problem: You need to implement a stack data structure that can also report the minimum element in constant-time. Solution Method 1 - Using extra stack This is not all that difficult if you think about it. Regular stacks support push() and pop() functions. We need to add a new read-only property, Minimum. You can’t just add a new variable to track the minimum because when the stack is popped you wouldn’t be know how to update the minimum variable without scanning through all items in the stack which would require you to pop and re-push each item, which is downright ugly. [Read More]