棒球比赛

class Solution:
    def calPoints(self, ops: List[str]) -> int:
        length = len(ops)
        score = [0]*(length)
        score[0] = ops[0]
        i=1
        while i <= length-1:
            if isinstance(ops[i],int):
            if 
                score[i] = ops[i]
            elif ops[i] == "+":
                if i == 1:
                    score[i] = score[i-1]
                else:
                    score[i] = score[i-1] + score[i-2]
            elif ops[i] == "D":
                score[i] = 2 * score[i-1]
            elif ops[i] == "C":
                score[i-1] = 0
                score[i] = 0
            i += 1
        return sum(score)
        
        

https://leetcode-cn.com/problems/baseball-game/

 

上面那种做法没有用栈，是错误的，下面正确（自己做）

class Solution:
    def calPoints(self, ops: List[str]) -> int:
        length = len(ops)
        res = []
        for i in range(0,length):
            if ops[i]!="+" and ops[i]!="D" and ops[i]!="C":
                res.append(int(ops[i]))
            elif ops[i] == "+":
                res.append(res[-1]+res[-2])
            elif ops[i] == "C":
                res.pop()
            elif ops[i]=='D':
                res.append(2*res[-1])
        return(sum(res))