20. Valid Parentheses

Description:

Solution:

In pariHash, we set close parentheses as a key, and open parentheses as a value.

If the c is open parentheses, we append on stack.

If the c is closing parentheses, we search the last value of stack "stack[-1]" and compare it with its key.

We can pop the stack.

 

If the stack is empty at the end of the solution, we can return True.

 

Time Complexity: O(n)

Space Complexity: O(n)