#1238
Circular Permutation in Binary Representation
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math · backtracking · bit manipulation
Description
Given 2 integers n and start. Your task is return any permutation p of (0,1,2.....,2n -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[2n -1] must also differ by only one bit in their binary representation.
Example 1:
Input: n = 2, start = 3
Output: [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 = 2
Output: [2,6,7,5,4,0,1,3]
Explanation: The binary representation of the permutation is (010,110,111,101,100,000,001,011).
Solution