Rotate An Array

October 12, 2010

Today’s exercise is simple but tricky: write a function to rotate the elements of an array. The function takes two arguments: the array to be rotated and the number of elements to rotate, where a positive count rotates to the left and a negative count rotates to the right. For instance, given the array [1 2 3 4 5 6], a rotation of 2 to the left gives [3 4 5 6 1 2], and a further rotation of 2 to the right restores the original array.

You should be sure to handle the edge cases properly. If the count is zero or the length of the array, the array should remain unchanged. If the count is greater than the length of the array, you should still do the right thing; for instance, a rotation of 8 on the array given above gives [3 4 5 6 1 2], the same as a rotation of 2.

Your task is to write the rotate function described above. When you are finished, you are welcome to read or run a suggested solution, or to post your own solution or discuss the exercise in the comments below.

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