void () { int[][] change = buildChange(new int[]{1, 2, 3}, new int[]{4, 5, 6}); assertNull(change); change = buildChange(new int[]{1, 2, 1}, new int[]{1, 3, 1}); assertNull(change); change = buildChange(new int[]{1, 2, 3, 3, 2, 1}, new int[]{1, 2, 3}); assertNull(change); change = buildChange(new int[]{1, 2, 3}, new int[]{1, 2, 3, 3, 2, 1}); assertNull(change); change = buildChange(new int[]{1, 2, 3}, new int[]{1, 2, 3, 3, 2, 1}); assertNull(change); change = buildChange(new int[]{1, 2, 1}, new int[]{2, 1, 2}); assertNull(change); change = buildChange(new int[]{}, new int[]{2, 1, 2}); assertNull(change); change = buildChange(new int[]{1, 2, 2}, new int[]{}); assertNull(change); change = buildChange(new int[]{}, new int[]{}); assertNull(change); }