baseball game

app.py

# You are keeping score for a baseball game with strange rules. The game consists of several rounds, where the scores of past rounds may affect future rounds' scores.

# At the beginning of the game, you start with an empty record. You are given a list of strings ops, where ops[i] is the ith operation you must apply to the record and is one of the following:

# An integer x - Record a new score of x.
# "+" - Record a new score that is the sum of the previous two scores. It is guaranteed there will always be two previous scores.
# "D" - Record a new score that is double the previous score. It is guaranteed there will always be a previous score.
# "C" - Invalidate the previous score, removing it from the record. It is guaranteed there will always be a previous score.


########## Steps:
# loops through a list
# looks for the ones that are number and push them into a stack
# check if the next character loop is "C". if it is, pop your stack list
# check if the next character loop is "D". if it is, double the last element in the stack list
# check if the next character loop is "+". if it is, sum the recent last two stack and add them back to the stack

class Solution:
    def isNumber(self, s):
        s = s.strip()
        try:
            s = float(s)
            return True
        except:
            return False
    
    def calPoints(self, ops: List[str]) -> int:
        score_history = []
        
        for i in ops:
            if self.isNumber(i):
                score_history.append(int(i))
            elif i == "C":
                score_history.pop()
            elif i == "D":
                score_history.append(score_history[-1] * 2)

            elif i == "+":
                score_history.append(score_history[-1] + score_history[-2])
        
        return sum(score_history)