Given 2 integers n and start. Your task is return any permutation p of (0,1,2.....,2^n -1) such that :
p[0] = startp[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 = 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).
Constraints:
1 <= n <= 160 <= start < 2 ^ nstruct Solution;
impl Solution {
fn circular_permutation(n: i32, start: i32) -> Vec<i32> {
let mut res = vec![];
for i in 0..1 << n {
res.push(start ^ (i ^ i >> 1));
}
res
}
}
#[test]
fn test() {
let n = 2;
let start = 3;
let res = vec![3, 2, 0, 1];
assert_eq!(Solution::circular_permutation(n, start), res);
let n = 3;
let start = 2;
let res = vec![2, 3, 1, 0, 4, 5, 7, 6];
assert_eq!(Solution::circular_permutation(n, start), res);
}