1 """
2 Given two integers dividend and divisor, divide two integers without using multiplication, division and mod operator.
3 Return the quotient after dividing dividend by divisor.
4 The integer division should truncate toward zero.
5 Example 1:
6 Input: dividend = 10, divisor = 3
7 Output: 3
8 Example 2:
9 Input: dividend = 7, divisor = -3
10 Output: -2
11 """
12 """
13 正确答案，先减第一个，再减double
14 """
15 class Solution:
16 def divide(self, dividend: int, divisor: int) -> int:
17 res = 0
18 positive = (dividend < 0) is (divisor < 0)
19 dividend = abs(dividend)
20 divisor = abs(divisor)
21 while dividend >= divisor:
22 temp, i = divisor, 1
23 while dividend >= temp: #多加了一层循环，是为了避免超时
24 res += i
25 dividend -= temp
26 i = 2*i
27 temp = 2*temp
28 if not positive:
29 res = - res
30 return min(max(-2147483648, res), 2147483647) #!!!这个范围限制很巧妙
31
32 """
33 我的答案，一个一个减会超时
34 """
35 class Solution:
36 def divide(self, dividend, divisor):
37 neg = 0
38 res = 0
39 if dividend > 0 and divisor < 0 or divisor > 0 and dividend < 0:
40 neg = 1
41 dividend = abs(dividend)
42 divisor = abs(divisor)
43 while dividend >= divisor:
44 dividend = dividend - divisor
45 res += 1
46 if neg:
47 res = - res
48 return min(max(-2147483648, res), 2147483647)
