## Stacks And Queues

##### Validity of a String

This function checks whether a given string containing only '(', ')' and '*' characters is valid. A string is considered valid if it follows the rules defined above.

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Dec 13
##### Stack sum function

Given a stack of integers, the function returns the sum of the elements in the stack.

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Dec 11
##### Check if a string of parentheses is balanced.

This function takes in a string consisting only of parentheses and outputs whether or not the string is balanced. A string is balanced if every open parenthesis has a corresponding close parenthesis and there are no unmatched parentheses.

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Dec 10
##### Return the sum of integers at even indices

This problem asks the programmer to return the sum of all integers at even indices in a given list. For example, given the list [1, 2, 3, 4, 5], the output would be 6 (2 + 4).

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Dec 09
##### Evaluating a Simple Expression String

Given a simple expression string consisting of parentheses, plus/minus signs, and non-negative integers, implement a basic calculator to evaluate the string.

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Dec 08
##### Stack Order Checker

The function should return true if the stack is in sorted order (increasing order), and false otherwise.

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Dec 06
##### Reverse a string using a stack

This problem asks you to reverse a string using a stack. An example input and output is provided.

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Dec 05
##### Design a stack with push, pop, and min operations in constant time.

A stack is a data structure that supports push, pop, and min operations in constant time.

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Dec 04