leetcode之Basic Calculator II

最新推荐文章于 2025-07-15 10:26:18 发布

howtogetout

最新推荐文章于 2025-07-15 10:26:18 发布

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文章标签： leetcode python 数据结构 Basic Calculator II

本文链接：https://blog.youkuaiyun.com/howtogetout/article/details/49936519

本文介绍了一个进阶版计算器的Python实现方法，通过使用列表来分别存储数字和运算符，并利用正则表达式处理输入字符串，支持加减乘除运算。

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跟Basic Calculator I差不多，只不过这次是增加了乘除，运用数据结构的基础知识做题。代码如下：

class Solution(object):
    def calculate(self, s):
        """
        :type s: str
        :rtype: int
        """
        import re
        listofnum = []
        listofsym = []
        symbol = ['*', '/', '+', '-']
        #空集
        if len(s) == 0:
            return 0
        #一个字母
        try:
            return int(s)
        except:
            #将所有项分别列出来
            s = re.sub(' ', '', s)
            n = ''
            for i in range(len(s)):
                try:
                    if s[i] in symbol:
                        listofnum.append(int(n))
                        listofsym.append(s[i])                        
                        n = ''
                    elif i == len(s) - 1:
                        n = n + s[i]
                        listofnum.append(int(n))
                    else:
                        n = n + s[i]
                except:
                    listofsym.append(s[i])
                #计算乘除
                if s[i] in ['+', '-']:
                    a = listofsym.pop()
                    if listofsym != []:
                        if listofsym[-1] in ['*', '/']:
                            listofnum1 = []
                            listofsym1 = []
                            listofnum1.append(listofnum.pop())
                            try:
                                while listofsym[-1] not in ['+', '-']:
                                    listofsym1.append(listofsym.pop())
                                    listofnum1.append(listofnum.pop())
                            except:
                                listofnum1 = listofnum1
                                listofsym1 = listofsym1
                            for i in listofsym1[::-1]:
                                a1 = listofnum1.pop()
                                b1 = listofnum1.pop()
                                if i == '*':
                                    listofnum1.append(a1 * b1)
                                else:
                                    if a1 > 0:
                                        if b1 > 0:
                                            listofnum1.append(a1 / b1)
                                        else:
                                            listofnum1.append(-(a1 / (-b1)))
                                    else:
                                        if b1 > 0:
                                            listofnum1.append(-(-a1 / b1))
                                        else:
                                            listofnum1.append(a1 / b1)
                            listofnum.append(listofnum1[0])
                    listofsym.append(a)
            #计算最后的
            if listofsym[-1] in ['*', '/']:
                listofnum1 = []
                listofsym1 = []
                listofnum1.append(listofnum.pop())
                while listofsym != []:
                    if listofsym[-1] not in ['+', '-']:
                        listofsym1.append(listofsym.pop())
                        listofnum1.append(listofnum.pop())
                    else:
                        break
                for i in listofsym1[::-1]:
                    a1 = listofnum1.pop()
                    b1 = listofnum1.pop()
                    if i == '*':
                        listofnum1.append(a1 * b1)
                    else:
                        if a1 > 0:
                            if b1 > 0:
                                listofnum1.append(a1 / b1)
                            else:
                                listofnum1.append(-(a1 / (-b1)))
                        else:
                            if b1 > 0:
                                listofnum1.append(-(-a1 / b1))
                            else:
                                listofnum1.append(a1 / b1)
                listofnum.append(listofnum1[0])
            while len(listofsym) != 0:
                a = listofnum.pop()
                b = listofnum.pop()
                try:
                    if listofsym[-1] == '-':
                        if listofsym[-2] == '-':
                            listofnum.append(a + b)
                        else:
                            listofnum.append(b - a)
                    else:
                        if listofsym[-2] == '-':
                            listofnum.append(b - a)
                        else:
                            listofnum.append(b + a)
                    listofsym.pop()
                except:
                    if listofsym[-1] == '-':
                        return b - a
                    else:
                        return a + b
            return listofnum[0]