問題： 計算字符串“10+12*13-30/20”的值

思路：

第一步：從左到右解析字符串，將數值與運算符放入數組

第二步：先計算乘除法，將求值放入隊列

第三步：依次出隊列，計算最終值

python代碼實現如下：

#!/usr/bin/python # -*- coding: utf-8 -*- import sys cal_string = '10+12*13-30/20' #分隔字符串 symbol = ['+', '-', '*', '/'] one_word = '' data = [] for c in cal_string:if c not in symbol:one_word += celse:data.append(int(one_word))data.append(c)one_word = '' data.append(one_word) print data#計算乘除，將運算完的值入隊列 hign_symbol = ['*', '/'] queue = [] cur_symbol = '' for one in data:if cur_symbol == '':if one in hign_symbol:cur_symbol = one else:queue.append(one)else:last_one = queue.pop()if cur_symbol == '*':new_one = float(last_one) * float(one) queue.append(new_one)else:new_one = float(last_one) / float(one)queue.append(new_one)cur_symbol = '' print queue#將隊列數據出隊列，計算最后值 result = 0 cur_symbol = '' for one in queue:if one != '+' and one != '-':if cur_symbol == '':result = oneelse:if cur_symbol == '+':result = result + oneelse:result = result - oneelse:cur_symbol = one print result 輸出結果：

[10, '+', 12, '*', 13, '-', 30, '/', '20'] [10, '+', 156.0, '-', 1.5] 164.5

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