tmhscs@gmail.com stacks

Stacks are a simple data structure where you can only modify the top element. This makes stacks a FILO (first-in-last-out) or LIFO (last-in-first-out) structure. Here are some of the methods that you will need to use and master:

Stack<TYPE> stack = new Stack<TYPE>(); // creates an empty stack
// TYPE should be replaced with a class name, like Integer or String
stack.push(VALUE); // pushes a value onto the top of the stack
stack.peek(); // returns the element on the top of the stack
stack.pop(); // removes AND returns the element on the top of the stack
stack.size(); // returns the number of elements in this stack
stack.clear(); // removes all values from this stack
stack.isEmpty(); // returns true or false if the stack has no elements in it
int pos = stack.search(VALUE); // returns the 1-based position of the value in the stack
// Search: If it returns 1, that means it is on top. If it returns -1, it isn't in the stack

NOTE, CODINGBAT DOES NOT COMPLETELY SUPPORT STACKS
ON MANY QUESTIONS YOU WILL HAVE TO DO THE FOLLOWING:

START PROBLEM WITH:
    Stack<Integer> stack = new Stack<Integer>();
    stack.addAll(list);
IF PROBLEM HAS ARRAYLIST AS RETURN VALUE, END PROBLEM WITH:
    return new ArrayList<Integer>(stack);

Easy Problems:
01. stack_makeStack H   stack_makeStack
02. stack_numberOfElements H   stack_numberOfElements
03. stack_peekStack H   stack_peekStack
04. stack_popStack H   stack_popStack
05. stack_secondElement H   stack_secondElement
06. stack_searchStack H   stack_searchStack
07. stack_searchAndPushIndex H   stack_searchAndPushIndex
08. stackHead7  stackHead7
09. stackHead7b  stackHead7b
10. stackHeadNot3  stackHeadNot3
11. stackHeadNot3b  stackHeadNot3b
12. stackHeadPlus8  stackHeadPlus8
13. stackHeadPlus8b  stackHeadPlus8b

Medium Problems:
14. stacks_pushIt H   stacks_pushIt
15. stackTail7  stackTail7
16. stackAdd1  stackAdd1
17. sumStack  sumStack
18. sumStackAdd  sumStackAdd
19. stackRemove4  stackRemove4
20. stackMin  stackMin

Hard Problems:
21. isSorted  isSorted
22. balanceBrackets  balanceBrackets video tutorial: https://youtu.be/CCyEXcNamC4?t=87

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