LeetCode/ValidParentheses.java at master · mehta128/LeetCode · GitHub

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 class ValidParentheses{
 public boolean isValid(String s) {
        int count = s.length();

        if(count == 0){
            return true;
        }

        boolean valid = true;

        ArrayList<Character> paranthese = new ArrayList<Character>();
        for(int i=0;i<count;i++){

           if(s.charAt(i) == '(' || s.charAt(i) == '{' || s.charAt(i) == '['){
               paranthese.add(s.charAt(i));
           } else if(paranthese.size()>0){

               int lastIndex =paranthese.size() -1;

               if(s.charAt(i) == ')' && paranthese.get(lastIndex) == '('){
                   paranthese.remove(lastIndex);
                   continue;
               }

               if(s.charAt(i) == '}' && paranthese.get(lastIndex) == '{'){
                   paranthese.remove(lastIndex);
                   continue;
               }

                if(s.charAt(i) == ']' && paranthese.get(lastIndex) == '['){
                   paranthese.remove(lastIndex);
                   continue;
               }

               valid = false;
               break;


           }else{
               valid = false;
                break;
           }


        }

        if(paranthese.size()> 0){

            return false;
        } else{
            return valid;
        }

    }
    }