加法运算替代

# -*- coding:utf-8 -*-
class AddSubstitution:
    def calc(self, a, b, t):
        if t == -1:
            return self.minus(a, b)
        elif t == 1:
            return self.multiply(a, b)
        else:
            return self.divide(a, b)
        
    def minus(self, a, b):
        return self.negate(b) + a
    
    def multiply(self, a, b):
        result = sum([a for i in range(0, abs(b))])
        if b < 0:
            result = self.negate(result)
            
        return result
    
    def divide(self, a, b):
        # a = xb 同乘法类似
        absa = abs(a)
        absb = abs(b)
        x = 0
        pro = 0
        while pro + absb <= absa:
            pro += absb
            x += 1
        
        if (a > 0 and b >0) or (a < 0 and b < 0):
            return x
        else:
            return self.negate(x)
    
    def negate(self, x):
        neg = 0
        d = 1 if x < 0 else -1
        while x != 0 :
            neg += d
            x += d
        
        return neg