Baseball Game — Stack Simulation

# Python
def calPoints(ops):
    stack = []
    for op in ops:
        if op == '+': stack.append(stack[-1] + stack[-2])
        elif op == 'D': stack.append(2 * stack[-1])
        elif op == 'C': stack.pop()
        else: stack.append(int(op))
    return sum(stack)

// Java
public int calPoints(String[] ops) {
    Deque<Integer> stack = new ArrayDeque<>();
    for (String op : ops) {
        if (op.equals("+")) { int a = stack.pop(), b = stack.peek(); stack.push(a); stack.push(a+b); }
        else if (op.equals("D")) stack.push(2 * stack.peek());
        else if (op.equals("C")) stack.pop();
        else stack.push(Integer.parseInt(op));
    }
    return stack.stream().mapToInt(Integer::intValue).sum();
}