题目
Given two numbers arr1
and arr2
in base -2, return the result of adding them together.
Each number is given in array format: as an array of 0s and 1s, from most significant bit to least significant bit.
For example, arr = [1,1,0,1]
represents the number (-2)^3 + (-2)^2 + (-2)^0 = -3
.
A number arr
in array format is also guaranteed to have no leading zeros: either arr == [0]
or arr[0] == 1
.
Return the result of adding arr1
and arr2
in the same format: as an array of 0s and 1s with no leading zeros.
Example
Input: arr1 = [1,1,1,1,1], arr2 = [1,0,1]
Output: [1,0,0,0,0]
Explanation: arr1 represents 11, arr2 represents 5, the output represents 16.
思路
这是一个最简单的解题思路。先将-2进制的数组转为10进制,然后再将10进制相加的结果转回-2进制。
本题还有不少的优化空间,可以使用carry bit(进位位)来优化代码,以后有时间了来补上。
Code
class Solution:
def addNegabinary(self, arr1: List[int], arr2: List[int]) -> List[int]:
n1 = self.negabinaryToNum(arr1)
n2 = self.negabinaryToNum(arr2)
return self.numToNegabinary(n1 + n2)
def negabinaryToNum(self, arr: List[int]) -> int:
result = 0
for i in range(len(arr)):
result += arr[-(i+1)] * pow(-2, i)
return result
def numToNegabinary(self, num: int) -> List[int]:
if num == 0:
return [0]
result = []
while num:
result.append(num&1)
num = -(num >> 1)
return result[::-1]