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Given 2 integers n
and start
. Your task is return any permutation p
of (0,1,2.....,2^n -1)
such that :
p[0] = start
p[i]
and p[i+1]
differ by only one bit in their binary representation.p[0]
and p[2^n -1]
must also differ by only one bit in their binary representation.
Example 1:
Input: n = 2, start = 3Output: [3,2,0,1]Explanation: The binary representation of the permutation is (11,10,00,01). All the adjacent element differ by one bit. Another valid permutation is [3,1,0,2]
Example 2:
Input: n = 3, start = 2Output: [2,6,7,5,4,0,1,3]Explanation: The binary representation of the permutation is (010,110,111,101,100,000,001,011).
Constraints:
1 <= n <= 16
0 <= start < 2 ^ n
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格雷码,需要知道两点:
1. 格雷码对应卡诺图,所以可以循环:
2. 格雷码的计算可以通过i^(i>>1),其实i=range(n),代码为
class Solution: def circularPermutation(self, n, start): return [start ^ i ^ (i>>1) for i in range(1<
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