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Copy pathgray_code.py
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37 lines (30 loc) · 1.06 KB
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#! /usr/bin/python
'''
The gray code is a binary numeral system where two successive values differ in only one bit.
Given a non-negative integer n representing the total number of bits in the code, print the sequence of gray code. A gray code sequence must begin with 0.
For example, given n = 2, return [0,1,3,2]. Its gray code sequence is:
00 - 0
01 - 1
11 - 3
10 - 2
'''
# The code does not pass OJ test cases due to the limiation of LeetCode
class Solution:
# @return a list of integers
def grayCode(self, n):
gray_code = []
if n == 0:
return []
gray_code = []
for index in range(1, n+1):
if index == 1:
gray_code.extend(['0', '1'])
continue
prev_code = gray_code
gray_code = []
gray_code.extend([ code + '0' for code in prev_code ])
gray_code.extend([ code + '1' for code in prev_code[::-1] ])
return [ int(code, 2) for code in gray_code ]
if __name__ == '__main__':
solution = Solution()
print solution.grayCode(2)