public static void Merge(int[] arr,int p,int q,int r ) { int n1 = q-p; int n2 = r-q; int[] L=new int[n1]; int[] R = new int[r-n2]; for (int i =
You get an Index out of bounds exception in this part:
for (int i = 0; i < n2; i++) R[i] = arr[q+i];
Your R-array is of size 0, while n2 is defined as 12 with the given arguments.