Valid Parentheses - Implementation

Here's the solution:

function isValid(s)
    stack := empty stack
    matchingBracket := {'(': ')', '{': '}', '[': ']'}

    for each char in s
        if char is in matchingBracket  // it's an open bracket
            push char onto stack
        else  // it's a close bracket
            if stack is empty
                return false
            top := pop from stack
            if matchingBracket[top] != char
                return false

    return stack is empty

Time: $O(n)$. Space: $O(n)$ in the worst case.