用python實現簡單的調度場演算法

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#因本人水平有限，目前只是簡單實現了調度場演算法，只支援+,-,*,/,%操作。其他待補充

#!/usr/bin/env python3# -*- coding:utf-8 -*-from sys import argvfrom decimal import *def delBlank(str):    """    Delete all blanks in the str    """    ans = ""    for e in str:        if e != " ":            ans += e    return  ansdef getPriority(c):    """    操作符中："+、-優先順序低，*、/、%優先順序高" ,^待續    """    if (c==‘+‘ or c==‘-‘):        return 0    elif(c == ‘*‘ or c == ‘/‘ or c == ‘%‘):        return  1    elif (c==‘^‘):        return 2def infix2postfix(str):    """    把中值運算式轉化為後值運算式。    """    postfix = []    stackOfOperator = []    index,pos,length = -1,0,len(str)    while(index < length-1):#python for index in range(length):不行，不館迴圈內是否更改index，index都是會從1到length-1。        index +=1        char = str[index]        if(char in "0123456789"):#如果是數字，直接輸出            pos = index            while(index <length and str[index] in "0123456789"):                index +=1            postfix.append(str[pos:index])            index -= 1            continue        elif(char == ‘)‘):#)右括弧，將棧中元素彈出只至左括弧，且左括弧和右括弧不加入到尾碼運算式            while(True):                tmp = stackOfOperator.pop()                if(tmp=="("):                    break                postfix.append(tmp)        elif(char == "("):#左括弧直接壓入棧中            stackOfOperator.append(char)        else:            if len(stackOfOperator) == 0:#如果棧為空白，則直接壓入                stackOfOperator.append(char)                continue            top = stackOfOperator[-1]            if (top == ‘(‘):#操作符棧頂為左括弧(，則將當前操作符入棧。                stackOfOperator.append(char)                continue            if(getPriority(char)<=getPriority(top)):            #如果此操作符(+,-,*,/,%)的優先順序小於或等於棧頂的元素            #則將棧中元素彈出至(1)遇到左括弧(2)棧頂元素為更低優先順序(3)棧為空白為止            #並將彈出的元素加入尾碼運算式中，將單曲運算元壓入棧中                while(True):                    tmp = stackOfOperator[-1]                    if(tmp == ‘(‘ or tmp == getPriority(tmp) < getPriority(char)):                        break                    postfix.append(tmp)                    stackOfOperator.pop()                    if len(stackOfOperator)==0:                        break                stackOfOperator.append(char)            else:            #如果當前操作符優先順序大於此時當前棧頂運算元，則講當前運算元壓入棧                stackOfOperator.append(char)    while(len(stackOfOperator)):        postfix.append(stackOfOperator.pop())    return postfixdef operate(num1,num2,operator):    if operator == "+":        return num1 + num2    elif operator == "-":        return num1 - num2    elif operator == "*":        return  num1 * num2    elif operator == "/":        return num1 / num2    elif operator == "%":        return num1 % num2    elif operator == "^":        return num1 ** num2‘‘‘通過尾碼運算式計算數值1、從左到有遍曆運算式的每個數字和符號，若是遇到數字則進棧，遇到運算子則將棧頂兩個元素出棧，進行運算並將運算結果進棧2、遍曆完尾碼運算式，此時棧中剩餘的數字就是運算結果‘‘‘def calculateByPostfix(postifix):    stackOfNumber =[]    index,length = 0,len(postifix)    while index < length:        e = postifix[index]        if e in "+-*/%":#後進先出            num2 = float(stackOfNumber.pop())            num1 = float(stackOfNumber.pop())            stackOfNumber.append(operate(num1,num2,e))            print(stackOfNumber)        else:            stackOfNumber.append(e)            print(stackOfNumber)        index += 1    return stackOfNumberif __name__ == ‘__main__‘:#get the exp    exp = ""    for i in range(len(argv)-1):        exp += argv[i+1]    exp = delBlank(exp)    postfix=infix2postfix(exp)    print(postfix)    print(calculateByPostfix(postfix))

　　

用python實現簡單的調度場演算法