Sorting Algorithms — Animate | AI Wisdom

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🎞 ANIMATE · Mode 3 of 5 · +100 XP— QuickSort
🎯Pivot
✂️Partition
📌Place
🔁Recurse
🎯 Next: Test →
Step 1 / 4
Speed
Choose pivot
Pivot = arr[hi] = 2. Partition [3,6,8,10,1,2,1] around 2💡 Analogy
Pick a "judge" value. Everyone smaller goes left, everyone larger goes right.
The pivot element (last element = 1) divides the array into "smaller than pivot" and "larger than pivot".
Console Output
> arr: [3,6,8,10,1,2,1]
> pivot = arr[6] = 1
> i = -1
●quicksort.ts
Choose pivotL3–4
1function quickSort(arr: number[], lo = 0, hi = arr.length - 1): number[] {
2  if (lo >= hi) return arr;       // Base case
3 
4  const pivot = arr[hi];          // Choose last element as pivot
5  let i = lo - 1;                 // Pointer for smaller elements
6 
7  for (let j = lo; j < hi; j++) {
8    if (arr[j] <= pivot) {
9      i++;
10      [arr[i], arr[j]] = [arr[j], arr[i]]; // Swap smaller to left
11    }
12  }
13 
14  [arr[i + 1], arr[hi]] = [arr[hi], arr[i + 1]]; // Place pivot
15  const pi = i + 1;               // Pivot index
16 
17  quickSort(arr, lo, pi - 1);     // Sort left partition
18  quickSort(arr, pi + 1, hi);     // Sort right partition
19  return arr;
20}
21 
22quickSort([3, 6, 8, 10, 1, 2, 1]); // → [1,1,2,3,6,8,10]
22 lines
Timeline — 4 Steps
Choose pivot
Pivot = arr[hi] = 2. Partition [3,6,8,10,1,2,1] around 2💡 Analogy
Pick a "judge" value. Everyone smaller goes left, everyone larger goes right.
The pivot element (last element = 1) divides the array into "smaller than pivot" and "larger than pivot".
Console Output
> arr: [3,6,8,10,1,2,1]
> pivot = arr[6] = 1
> i = -1

Pivot = arr[hi] = 2. Partition [3,6,8,10,1,2,1] around 2

Pivot = arr[hi] = 2. Partition [3,6,8,10,1,2,1] around 2

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Pivot = arr[hi] = 2. Partition [3,6,8,10,1,2,1] around 2

Pivot = arr[hi] = 2. Partition [3,6,8,10,1,2,1] around 2

Was this page helpful?

Discussion