1. Start index
Start at index 1 so there is a left neighbor to compare.
let i = 1Typorithm · easy
Gnome Sort
▷ Interactive algorithm labgnome-sortsortingadjacent-swapsinsertion-sortquadratic-time
Saved on this device
Full lesson · 8 learning steps Open any exercise for focused practice
10%
Step 1 of 8 · intro card
Learn Gnome Sort
Sorting Algorithms
Gnome Sort walks forward through ordered pairs and steps backward whenever it swaps an out-of-order pair.
Gnome Sort feels like Insertion Sort expressed through adjacent swaps.
If the current pair is ordered, the pointer moves right.
If the pair is out of order, the algorithm swaps it and steps left.
Stepping left lets a small value keep moving back until it reaches its insertion position.
The algorithm is easy to trace but has O(n^2) worst-case time.
Preparing algorithm lab…
01
Compare arr[i - 1] and arr[i].
02
Move right when ordered.
03
Swap and move left when out of order.
04
Adjacent strict swaps make it stable.
05
Worst-case time is O(n^2).
function gnomeSort(arr) {
let i = 1;
while (i < arr.length) {
if (i === 0 || arr[i - 1] <= arr[i]) {
i++;
} else {
[arr[i - 1], arr[i]] = [arr[i], arr[i - 1]];
i--;
}
}
return arr;
}Read the implementation
Connect each part of the code to the concept before you type.
2. Walk array
Continue until the pointer walks beyond the last item.
while (i < arr.length)3. In-order pair
If the pair is in order, move forward.
i === 0 || arr[i - 1] <= arr[i]4. Step forward
Move right when the local order is fine.
i++5. Swap backward
Swap an out-of-order adjacent pair.
[arr[i - 1], arr[i]] = [arr[i], arr[i - 1]]6. Step backward
After swapping, step back to check whether the value must move farther left.
i--A complete learning loop
01
Understand
Read the concept map and follow the code breakdown.
02
Reconstruct
Type the implementation, repair mistakes and work through every recall exercise.
03
Verify
Use the final check without hints; revisit weak concepts in short practice sessions.