LeetCode in Kotlin
89. Gray Code
Medium
An n-bit gray code sequence is a sequence of 2n integers where:
- Every integer is in the inclusive range
[0, 2n - 1], - The first integer is
0, - An integer appears no more than once in the sequence,
- The binary representation of every pair of adjacent integers differs by exactly one bit, and
- The binary representation of the first and last integers differs by exactly one bit.
Given an integer n, return any valid n-bit gray code sequence.
Example 1:
Input: n = 2
Output: [0,1,3,2]
Explanation: The binary representation of [0,1,3,2] is [00,01,11,10]. - 00 and 01 differ by one bit - 01 and 11 differ by one bit - 11 and 10 differ by one bit - 10 and 00 differ by one bit [0,2,3,1] is also a valid gray code sequence, whose binary representation is [00,10,11,01]. - 00 and 10 differ by one bit - 10 and 11 differ by one bit - 11 and 01 differ by one bit - 01 and 00 differ by one bit
Example 2:
Input: n = 1
Output: [0,1]
Constraints:
1 <= n <= 16
Solution
@Suppress("NAME_SHADOWING")
class Solution {
fun grayCode(n: Int): List<Int?> {
var n = n
var n1 = arrayOf<Int?>(0)
var shift = 1
while (n > 0) {
val temp = arrayOfNulls<Int>(n1.size * 2)
var pos = 0
for (integer in n1) {
temp[pos++] = integer
}
for (i in n1.indices.reversed()) {
temp[pos++] = n1[i]!! or shift
}
n1 = temp
shift = shift shl 1
n--
}
return listOf(*n1)
}
}