➜ ~

Playing Hacks and Stuffs!

---

Project maintained by h4ckyou Hosted on GitHub Pages — Theme by mattgraham

Valid Parentheses

Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

An input string is valid if:

• Open brackets must be closed by the same type of brackets.
• Open brackets must be closed in the correct order.
• Every close bracket has a corresponding open bracket of the same type.

From the question we know that we’ll be given a string containing the symbols above

Our goal is to check if it’s a valid parenthesis

One way to approach this is to use the Stack Data Structure

The idea basically is this:

• We’ll push the opening parenthesis onto the stack if we find one
• Then when we encounter a closing parenthesis we pop the value from the stack and compare the mapping of the character in the hashtable if they are the same
• If they match we keep continuing the process till we traverse all characters in the string
• If after traversing we check if there’s value on the stack and if the string is a valid parenthesis they won’t be any value on the stack because it would have been popped out already
• So that’s going to be our return boolean value

Here’s my solve script: link

Leetcode Submission Script

class Solution:
    def isValid(self, s: str) -> bool:
        parenthesis = {')': '(', '}': '{', ']': '['}
        stack = []

        for char in s:
            if char in parenthesis.values():
                stack.append(char)
            
            elif char in parenthesis.keys():
                if not stack or stack.pop() != parenthesis[char]:
                    return False

        return len(stack) == 0