# “Valid Parentheses” Cheat Sheet javascript solution

--

The Valid Parentheses is in the easy category and is a good start for understanding more challenging algorithms using the stack and array as a data structure. I will focus on explaining a solution that works and not on the O time and space complexity.

Challenge:

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

An input string is valid if:

1. Open brackets must be closed by the same type of brackets.
2. Open brackets must be closed in the correct order.”LeetCode

Note:

`// String s// Determine if valid// Valid = same type brackets && open/closed in correct order// Empty string = true// Return boolean `

Example:

`Input: s = “[]”Output: true`

Explanation:

create a valid brackets object to compare to a stack that will store the string brackets and return true or false.

## 1.Create an object of valid brackets

`let validBracket = { ‘(‘:’)’, ‘{‘:’}’, ‘[‘:’]’ }`

## 2. Create an array to sort the stack

`let stack =[];`

## 3. Loop through the string s

`for (let char of s ) {`

## 4. Check if validBracket

`if (validBracket[char]){`

## 5. If valid push through the stack

stack.push(validBracket[char])

## 6. If the last character not equal to char it is false

`if (stack.pop()!== char ) return false`

## Solution:

`var isValid = function(s) {let validBracket = {‘(‘:’)’,‘{‘:’}’,‘[‘:’]’}let stack =[];for (let char of s ) {if (validBracket[char]){stack.push(validBracket[char])} else {if (stack.pop()!== char ) return false}}return (!stack.length)};`

--

--

Lifelong learner , Full Stack Software Engineer.