Branch-free left and right array rotation by K

For rotating a 1-D array by K, avoid repeated single-step shifts. Left rotation: place a[i] at (i-k+n)%n. Right rotation: place a[i] at (i+k)%n. Normalise K first with ((k%n)+n)%n so negative or oversized K is handled. Each is a single O(n) loop into a fresh array.