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# 四则运算行棋 计算器
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"""|||mid_to_aft：将中缀表达式转化为后缀表达式l;
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aft_to_cal：有参数l，将后缀表达式进行计算；
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mid_to_cal：直接将中缀表达式进行计算。|||"""
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class Calculator(object): # 用一个类应用于计算
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def __init__(self, equ):
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self.s = equ
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def mid_to_aft(self):
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pref = {'+': 1, '-': 1, '*': 2, '/': 2, '^': 3} # 符号字典
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l = ''
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A = []
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i = 0
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while True:
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loc = self.s[i]
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# 可能是一个两位以上的数字
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if loc in list('0123456789'):
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while i < len(self.s) - 1 and self.s[i + 1] in list('0123456789'): # 不是最后一个数字且为连续数字
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loc += self.s[i + 1]
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i += 1 # 刚好到连续的最后一个数字
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l = l + loc + ' '
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elif loc in list('()+-*/^'):
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if A == [] or loc == '(':
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A.append(loc)
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elif loc == ')':
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while A[-1] != '(':
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l = l + A.pop() + ' '
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A.pop()
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elif A[-1] == '(':
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A.append(loc)
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else:
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if pref[loc] > pref[A[-1]]:
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A.append(loc)
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else:
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while A[-1] != '(':
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l = l + A.pop() + ' '
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if A == []:
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break
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A.append(loc)
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i += 1
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if i == len(self.s):
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while A != []:
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if len(A) == 1:
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l += A.pop()
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else:
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l = l + A.pop() + ' '
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break
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return l
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def aft_to_cal(self, l):
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A = []
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i = 0
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while True:
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# print('第{}个元素：A = '.format(i+1),A)
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loc = l[i]
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if loc in list('0123456789'):
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while l[i + 1] in list('0123456789'): # 此时肯定是数字
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loc += l[i + 1]
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i = i + 1
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A.append(float(loc))
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i += 1
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elif loc == ' ':
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i += 1
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continue
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else:
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if loc == '+':
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A.append(A.pop() + A.pop())
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elif loc == '-':
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A.append(-A.pop() + A.pop())
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elif loc == '*':
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A.append(A.pop() * A.pop())
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elif loc == '/':
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A.append((1 / A.pop()) * A.pop())
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else:
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last = A.pop()
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A.append(pow(A.pop(), last))
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i += 1
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if i >= len(l) - 1:
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break
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result = A.pop()
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return result
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def mid_to_cal(self):
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pref = {'+': 1, '-': 1, '*': 2, '/': 2, '^': 3}
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l = ''
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A = []
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i = 0
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while True:
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loc = self.s[i]
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# 可能是一个两位以上的数字
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if loc in list('0123456789'):
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while i < len(self.s) - 1 and self.s[i + 1] in list('0123456789'): # 不是最后一个数字且为连续数字
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loc += self.s[i + 1]
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i += 1 # 刚好到连续的最后一个数字
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l = l + loc + ' '
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elif loc in list('()+-*/^'):
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if A == [] or loc == '(':
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A.append(loc)
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elif loc == ')':
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while A[-1] != '(':
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l = l + A.pop() + ' '
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A.pop()
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elif A[-1] == '(':
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A.append(loc)
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else:
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if pref[loc] > pref[A[-1]]:
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A.append(loc)
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else:
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while A[-1] != '(':
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l = l + A.pop() + ' '
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if A == []:
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break
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A.append(loc)
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i += 1
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if i == len(self.s):
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while A != []:
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if len(A) == 1:
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l += A.pop()
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else:
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l = l + A.pop() + ' '
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break
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i = 0
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while True:
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loc = l[i]
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if loc in list('0123456789'):
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while l[i + 1] in list('0123456789'): # 此时肯定是数字
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loc += l[i + 1]
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i = i + 1
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A.append(float(loc))
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i += 1
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elif loc == ' ':
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i += 1
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continue
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else:
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if loc == '+':
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A.append(A.pop() + A.pop())
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elif loc == '-':
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A.append(-A.pop() + A.pop())
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elif loc == '*':
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A.append(A.pop() * A.pop())
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elif loc == '/':
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A.append((1 / A.pop()) * A.pop())
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else:
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last = A.pop()
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A.append(pow(A.pop(), last))
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i += 1
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if i >= len(l) - 1:
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break
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result = A.pop()
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return result
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'''def eval(expression):
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c = eval(expression)
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return c'''
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'''中缀转后缀计算器设计结束''' |
