Using temp array:
Input arr[ ] = [1, 2, 3, 4, 5, 6, 7], d = 2, n =7
1) Store d elements in a temp array
temp[ ] = [1, 2]
2) Shift rest of the arr[ ]
arr[ ] = [3, 4, 5, 6, 7, 6, 7]
3) Store back the d elements
arr[ ] = [3, 4, 5, 6, 7, 1, 2]