# AI solution for JavaScript Coding Question on BFE.dev

102. validate string of parentheses

One possible solution to this problem is to use a stack data structure to keep track of the opening brackets. Whenever we encounter an opening bracket, we push it onto the stack. Whenever we encounter a closing bracket, we pop a bracket from the stack and compare it with the closing bracket. If they match, we continue processing the string. If they don't match, we return false immediately.

If the string ends and the stack is empty, we return true. Otherwise, we return false, because there are still brackets that are not properly matched.

Here's the code:

`function validate(str) { const stack = []; for (let i = 0; i < str.length; i++) { const symbol = str[i]; if (symbol === '(' || symbol === '[' || symbol === '{') { stack.push(symbol); } else if (symbol === ')') { if (stack.pop() !== '(') { return false; } } else if (symbol === ']') { if (stack.pop() !== '[') { return false; } } else if (symbol === '}') { if (stack.pop() !== '{') { return false; } } } return stack.length === 0;}`

The time complexity of this solution is O(n), where n is the length of the input string. We iterate over the string once, and each stack operation takes constant time. The space complexity is also O(n), because the stack can contain up to n/2 bracket symbols.

There are some other possible solutions to this problem, such as using a regular expression or a recursive function. However, the stack-based solution is relatively simple and efficient, and can handle more complex bracket matching in other scenarios.