暴力:(会超时)
# encoding = utf-8
# 开发者:xxx
# 开发时间: 13:51
# "Stay hungry,stay foolish."
class Solution(object):
def divide(self, dividend, divisor):
if dividend != 1 and dividend != -1:
if divisor == 1:
return dividend
if divisor == -1:
if dividend >0:
dividend = str(dividend)
dividend = int("-" + dividend)
return dividend
elif dividend < 0 :
dividend = str(dividend)
dividend = int(dividend[1:])
return dividend
res = 0
if divisor > 0 and dividend > 0:
while dividend - divisor >= 0:
res += 1
dividend = dividend - divisor
elif dividend < 0 and divisor < 0:
while dividend - divisor <= 0:
res += 1
dividend = dividend - divisor
else:
if divisor < 0:
dividend = str(dividend)
dividend = int("-" + dividend)
while dividend - divisor <= 0:
res += 1
dividend = dividend - divisor
res = str(res)
res = int("-" + res)
else:
divisor = str(divisor)
divisor = int("-" + divisor)
while dividend - divisor <= 0:
res += 1
dividend = dividend - divisor
res = str(res)
res = int("-" + res)
if res > 2147483647:
res = 2147483647
return res
if __name__ == '__main__':
sol = Solution()
print(sol.divide(-214, -1))
技巧:
# encoding = utf-8
# 开发者:xxx
# 开发时间: 13:51
# "Stay hungry,stay foolish."
class Solution(object):
def divide(self, dividend, divisor):
bool = False
if divisor > 0 and dividend < 0 :
bool = True
elif divisor < 0 and dividend > 0 :
bool = True
dividend = abs(dividend)
divisor = abs(divisor)
count = 0
# 把除数不断左移,直到它大于被除数
while dividend >= divisor:
count += 1
divisor <<= 1
result = 0
while count > 0:
count -= 1
divisor >>= 1
if divisor <= dividend:
result += 1 << count # 这里的移位运算是把二进制(第count+1位上的1)转换为十进制
dividend -= divisor
if bool:
return -result
else:
if result > 2147483647:
result = 2147483647
return result
if __name__ == '__main__':
sol = Solution()
print(sol.divide(7, -3))
所用方法:
运算符 | 描述 | 实例 |
---|---|---|
& | 按位与运算符:参与运算的两个值,如果两个相应位都为1,则该位的结果为1,否则为0 | (a & b) 输出结果 12 ,二进制解释: 0000 1100 |
| | 按位或运算符:只要对应的二个二进位有一个为1时,结果位就为1。 | (a | b) 输出结果 61 ,二进制解释: 0011 1101 |
^ | 按位异或运算符:当两对应的二进位相异时,结果为1 | (a ^ b) 输出结果 49 ,二进制解释: 0011 0001 |
~ | 按位取反运算符:将二进制表示中的每一位取反,0 变为 1,1 变为 0。~x 类似于 -x-1 | (~a ) 输出结果 -61 ,二进制解释: 1100 0011 (以补码形式表示),在一个有符号二进制数的补码形式。 |
<< | 左移动运算符:运算数的各二进位全部左移若干位,由 << 右边的数字指定了移动的位数,高位丢弃,低位补0。 | a << 2 输出结果 240 ,二进制解释: 1111 0000 |
>> | 右移动运算符:把">>"左边的运算数的各二进位全部右移若干位,>> 右边的数字指定了移动的位数 | a >> 2 输出结果 15 ,二进制解释: 0000 1111 |
以下实例演示了Python所有位运算符的操作:
实例(Python 2.0+)
#!/usr/bin/python
# -*- coding: UTF-8 -*-
a = 60 # 60 = 0011 1100
b = 13 # 13 = 0000 1101
c = 0
c = a & b; # 12 = 0000 1100
print
"1 - c 的值为:", c
c = a | b; # 61 = 0011 1101
print
"2 - c 的值为:", c
c = a ^ b; # 49 = 0011 0001
print
"3 - c 的值为:", c
c = ~a; # -61 = 1100 0011
print
"4 - c 的值为:", c
c = a << 2; # 240 = 1111 0000
print
"5 - c 的值为:", c
c = a >> 2; # 15 = 0000 1111
print
"6 - c 的值为:", c
以上实例输出结果:
1 - c 的值为: 12 2 - c 的值为: 61 3 - c 的值为: 49 4 - c 的值为: -61 5 - c 的值为: 240 6 - c 的值为: 15