Staaarter Tools

Integer Rotator

Cyclically rotates the ORDER of a list of integers by a chosen number of positions, wrapping values that fall off one end back onto the other; positive positions rotate right (toward the end), negative positions rotate left. A free online tool from Staaarter, right in your browser.

Runs locallyUpdated 2026-07-27
integerlistreordering

Overview

Introduction

Rotating a list cyclically — wrapping the tail around to the front, or the front around to the tail — is a common building block in scheduling, round-robin assignment, and cipher-like puzzles.

This tool applies that rotation directly to a list of integers, letting you shift the whole sequence's order by any number of positions in either direction.

What Is Integer Rotator?

A list-reordering tool: it takes a list of integers and a Positions count, and produces the same values reordered by a cyclic rotation.

Unlike sorting, rotation never changes which values are in the list, only their relative starting point.

How Integer Rotator Works

The list is parsed one integer per line, with blank lines skipped and invalid lines rejected.

Positions is normalized into an equivalent non-negative shift using modular arithmetic, so both very large and negative values wrap correctly.

The list is split into two slices at the wrap point and swapped: the tail slice (of length equal to the shift) moves to the front, followed by the remaining head slice, producing a right rotation for positive Positions.

When To Use Integer Rotator

Use it to cycle through a fixed list of values in round-robin fashion, e.g. rotating which value is "first" each run.

It's also useful for exploring cyclic permutations of a small dataset for puzzles or scheduling logic.

Often used alongside Integer Digit Shifter and Integer Duplicator.

Features

Advantages

  • Handles any integer Positions value, including negative numbers and values larger than the list length, via modular wraparound.
  • Never changes the multiset of values in the list, only their order, so nothing is lost or duplicated.

Limitations

  • Only rotates order; it can't reverse, shuffle randomly, or sort the list.
  • Rejects an empty list rather than returning an empty result, since there's no meaningful rotation of nothing.

Examples

Rotating right by 1

Input

1
2
3
4
5

Output

5
1
2
3
4

With Positions=1, the last value (5) wraps around to the front, and everything else shifts one place toward the end.

Rotating left by 2 (negative Positions)

Input

1
2
3
4
5

Output

3
4
5
1
2

With Positions=-2, the first two values (1, 2) wrap around to the end, equivalent to rotating right by 3 on a 5-element list.

Best Practices & Notes

Best Practices

  • Use a Positions value modulo the list length if you want to reason about the smallest equivalent rotation.
  • Combine with Integer Duplicator beforehand if you want to rotate a list that includes deliberate repeated values.

Developer Notes

The rotation uses the standard `((positions % n) + n) % n` normalization to safely handle negative and over-large shifts, then splits the array into two slices at `n - shift` and concatenates them in swapped order, an O(n) operation with no explicit loop needed.

Integer Rotator Use Cases

  • Implementing round-robin ordering for a fixed list of participants, tasks, or resources
  • Exploring cyclic permutations of a small dataset for puzzles or algorithm teaching
  • Rotating a priority or schedule list by a fixed offset each run

Common Mistakes

  • Confusing this with Integer Digit Shifter, which rotates digits within numbers rather than the order of the list itself.
  • Expecting a Positions value larger than the list length to error out — it's handled correctly via modular wraparound instead.

Tips

  • A Positions value equal to the list length always returns the list unchanged, since a full rotation is a no-op.
  • Try both a positive and the equivalent negative Positions value to see the two directions of rotation side by side.

References

Frequently Asked Questions