682. Baseball Game

/*
682. Baseball Game
Runtime: 2 ms, faster than 87.95% of Java online submissions for Baseball Game.
Memory Usage: 38 MB, less than 93.69% of Java online submissions for Baseball Game.
*/


class Solution {
    public int calPoints(String[] ops) {
        Stack<Integer> s = new Stack<>();
            
        for(int i=0; i<ops.length; i++){
          
            switch(ops[i]){
                    
            case "D": 
                    int l = s.peek();
                    int d = 2 * l;
                    s.push(d);
                    break;
            case "C":
                    s.pop();
                    break;
            case "+":
                    int n = s.pop();
                    int sum = s.peek() + n;
                    s.push(n);
                    s.push(sum);
                    break;
            default:        
                   int num = Integer.parseInt(ops[i]);
                   s.push(num);
                    break;
            }
        }     
        
        int total = 0;
        
        while(!s.isEmpty()){
            total += s.pop();
        }
        return total;
        
    }
}