Leetcode Valid Paranthesis Problem

Suboor Khan

August 25, 2020

#Problem solving#Typescript

Solution of Leetcode Valid Paranthesis Problem

20. 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.

Example 1:

Input: s = "()"
Output: true

Example 2:

Input: s = "()[]{}"
Output: true

Example 3:

Input: s = "(]"
Output: false

Constraints:

1 <= s.length <= 104
s consists of parentheses only '()[]{}'.

Solution:

var mapOpenToClose: Record = {
        '(': ')',
        '{': '}',
        '[': ']'
    }


function isValid(s: string): boolean {
    if(s.length === 1) return false;
    const stack = [];
    for(let x = 0; x < s.length; x++) {
        let currentParan = s[x] // )
        if(mapOpenToClose[currentParan]) stack.push(currentParan) 
        else if(currentParan !== mapOpenToClose[stack[stack.length - 1]]) return false;
        else stack.pop()
    }
    return stack.length === 0
};