Function zigzag

cmp/internal/diff/diff.go:397–402

zigzag maps a consecutive sequence of integers to a zig-zag sequence. [0 1 2 3 4 5 ...] => [0 -1 +1 -2 +2 ...]

(x int)

//
//	[0 1 2 3 4 5 ...] => [0 -1 +1 -2 +2 ...]
func zigzag(x int) int {
	if x&1 != 0 {
		x = ^x
	}
	return x >> 1
}