682. Baseball Game

MA:

class Solution {
    public int calPoints(String[] ops) {
        Integer score=0;
        Stack<Integer> stack=new Stack<Integer>();
        for(int i=0;i<ops.length;i++){
            switch(ops[i]){
            case "D":
                stack.push(2*stack.peek());
                break;
            case "+":
                int temp=stack.pop();
                int insertBuffer=temp+stack.peek();
                stack.push(temp);
                stack.push(insertBuffer);
                break;
            case "C":
                stack.pop();
                break;
            default:
                stack.push(Integer.parseInt(ops[i]));
                break;
            }
        }
        while(stack.empty()!=true){
            score+=stack.pop();
        }
        return score;
    }
}

OA:
class Solution { public int calPoints(String[] ops) { int sum = 0; int[] valid = new int[ops.length]; int v = -1; for(int i = 0; i < ops.length; i++){ if(ops[i].equals("C")){ sum -= valid[v]; v--; } else if(ops[i].equals("D")){ int d = valid[v] + valid[v]; v++; valid[v] = d; sum += d; } else if(ops[i].equals("+")){ int p = valid[v] + valid[v - 1]; v++; valid[v] = p; sum += p; } else { int val = Integer.parseInt(ops[i]); v++; valid[v] = val; sum += val; } } return sum; } }
用数组做的

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