Validate the parenthesis in a string ensuring that all open parenthesis have a matching closing.

Question

Anonymous · Accepted Answer

Gave several ways to solve this problem, it is widely used as an interview question so I was very prepared for it. Solved with a stack, recursion, counter, and a mix then chose the best solution and explained why.

Anonymous · Answer

Stack parens = new Stack();
        
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            if (c == '(' || c == '[' || c == '{') parens.push(c);
            else if (c == ')' && !parens.empty() && parens.peek() == '(') parens.pop();
            else if (c == ']' && !parens.empty() && parens.peek() == '[') parens.pop();
            else if (c == '}' && !parens.empty() && parens.peek() == '{') parens.pop();
            else return false;
        }
        return parens.empty();

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