Solved challenge valid parenthesis #67
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I approached the problem using a stack, where on the top of the stack the last parenthesis is stored ("(", "{" or "["). On each character, an opening parenthesis is pushed onto the stack, and for a closed parenthesis the last item on the stack is popped and checked if it is equal to the current parenthesis. At the end of the string, the stack is checked if it is empty, because otherwise there would be an opening parenthesis without a closing one.
How to use the solution:
Just use the functoin
has_valid_parens(string)which returns True or False whether the given string has valid parenthesis.