Interview Question #10:
Write a function or program that checks if a string is a balanced parenthesis.🤔
If you need practice, try to solve this on your own without looking at the solution below.
Feel free to bookmark 🔖 even if you don't need this for now. You may need to refresh/review down the road when it is time for you to look for a new role.
Codepen:
If you want to play around and experiment with the code: https://codepen.io/angelo_jin/pen/OJgwaed
Solution below uses a stack which is a great algorithm to use in this kind of problem. With a small tweak on the code below, you can solve problem that checks for balanced curly braces, brackets and parenthesis as well.
function isBalanced(str) {
const stack = []
for (let char of str) {
if ( char === '(' ) {
stack.push(char)
} else {
if ( stack.pop() !== '(' ) {
return false
}
}
}
if (stack.length !== 0) return false
return true
}
Small Cleanup/Refactor
function isBalanced(str) {
const stack = []
for (let char of str) {
if ( char === '(' ) {
stack.push(char)
} else if ( stack.pop() !== '(' ) {
return false
}
}
return stack.length !== 0 ? false : true
}
Happy coding and good luck if you are interviewing!
Video below if you prefer instead of bunch of text/code.