Bit Manipulation Gray Code Sequence (Go)

package main

func grayCode(n int) []int {
	count := 1 << n
	result := make([]int, count)
	for i := 0; i < count; i++ { result[i] = i ^ (i >> 1) }
	return result
}

func popcount(x int) int {
	x = x - ((x >> 1) & 0x55555555)
	x = (x & 0x33333333) + ((x >> 2) & 0x33333333)
	x = (x + (x >> 4)) & 0x0f0f0f0f
	return (x * 0x01010101) >> 24
}