Java Data Structure #11

What I’ve Learned

First, I can use Stack<Character> for stack questions.

Disclaimer

For LeetCode, I started learning about data structures on Udemy. I’ve been studying with lecture named Java Data Structures & Algorithms + LEETCODE Exercises.

Stack: Reverse String

I can use Stack<Character> for the Stack questions. I didn’t know about Stack.

   public static String reverseString(String myString){
        Stack<Character> stack = new Stack<>();
        String reversedString = "";
        
        for(char c: myString.toCharArray()){
            stack.push(c);
        }
        
        while(!stack.isEmpty()){
            reversedString += stack.pop();
        }
        return reversedString;
    }

Stack: Parentheses Balanced

I know how to solve this. I can just check if there is value in stack and pop when it matches. But, this is a special case. It’s little bit different.

   public static boolean isBalancedParentheses(String paren){
        Stack<Character> stack = new Stack<>();
        for(char c : paren.toCharArray()){
            if(c=='(')
                stack.push(c);
            else if(c == ')')
                if(stack.isEmpty() || stack.pop() != '('){
                    return false;
                }
        }
        return stack.isEmpty();
    }