Start hereSwap neighbors
Bubble Sort
- Choose it when
- Learning comparison sorts for the first time
- Watch for
- The largest unsorted value moves right after every pass.
Sorting algorithms
Compare how algorithms order the same values through swaps, shifts, partitions, counting, and digit passes.
How should the data move?
Choose by the decision you want to understand
Each lesson names the situation it fits and the behavior worth watching.
BeginnerSelect a minimum
Selection Sort
- Choose it when
- Separating comparisons from writes
- Watch for
- Each pass performs many checks but at most one final swap.
BeginnerShift and insert
Insertion Sort
- Choose it when
- Understanding nearly sorted data
- Watch for
- A sorted prefix grows while larger values shift right.
IntermediateDivide and merge
Merge Sort
- Choose it when
- Learning stable O(n log n) sorting
- Watch for
- Small sorted runs combine without revisiting earlier decisions.
IntermediatePartition around a pivot
Quick Sort
- Choose it when
- Understanding in-place divide-and-conquer
- Watch for
- Values move to the correct side before the pivot is fixed.
IntermediatePromote and extract
Heap Sort
- Choose it when
- Connecting tree structure to array sorting
- Watch for
- The maximum repeatedly rises to the heap root, then leaves the heap.
SpecializedCount and place
Counting Sort
- Choose it when
- Small integer ranges with repeated values
- Watch for
- Value frequencies replace pairwise comparisons.
SpecializedSort one digit
Radix Sort
- Choose it when
- Fixed-width integers or identifiers
- Watch for
- Stable digit passes preserve the ordering earned earlier.
SpecializedDistribute and gather
Bucket Sort
- Choose it when
- Values spread across a known range
- Watch for
- Good bucket distribution turns one hard sort into several small ones.