rotateArray.java

  public static void reverse (int nums[],int start,int end) {
      while(start < end) {
          int tmp = nums[start];
          nums[start] = nums[end];
          nums[end] = tmp;
          start++;
          end--;
      }
  }
  
  public static void rotate(int[] nums, int k) {
      int n = nums.length;
      k %= n;
      reverse(nums,0,n-1);
      reverse(nums,0,k-1);
      reverse(nums,k,n-1);
  }