> For the complete documentation index, see [llms.txt](https://algorithm.prettylog.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://algorithm.prettylog.com/algorithm-problems/algoexpert/easy/insertion-sort.md).
# Insertion Sort
* best: N, 1
* average, worst: N^2, 1
* swap last
```jsx
function insertionSort(arr) {
for (let i = 1; i < arr.length; i++) {
const curr = arr[i];
let idx = i;
while (idx >= 1) {
if (curr >= arr[idx - 1]) break; // vale at curr i, has to be compared with all previous values
arr[idx] = arr[idx - 1]; // move backward by 1 step
idx--;
}
arr[idx] = curr;
}
return arr;
}
function swap(arr, a, b) {
[arr[b], arr[a]] = [arr[a], arr[b]];
}
// Do not edit the line below.
exports.insertionSort = insertionSort;
```
* swap every time
```jsx
function insertionSort(arr) {
for (let i = 1; i < arr.length; i++) {
const curr = arr[i];
let idx = i;
while (idx >= 1) {
if (curr >= arr[idx - 1]) break; // vale at curr i, has to be compared with all previous values
swap(arr, idx, idx - 1);
idx--;
}
}
return arr;
}
function swap(arr, a, b) {
[arr[b], arr[a]] = [arr[a], arr[b]];
}
// Do not edit the line below.
exports.insertionSort = insertionSort;
```
* simple
```jsx
function insertionSort(arr) {
for (let i = 1; i < arr.length; i++) {
// const base = arr[i];
let idx = i;
while (idx > 0) {
if (arr[idx - 1] <= arr[idx]) break;
[arr[idx - 1], arr[idx]] = [arr[idx], arr[idx - 1]];
idx--;
}
}
return arr;
}
// Do not edit the line below.
exports.insertionSort = insertionSort;
```
---
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