Sorting

Bubble sort vs Heap sort

Bubble sort and Heap sort both put an array in order, in different ways. Bubble sort: swap neighbors that are out of order. Heap sort: build a max-heap in the array, then repeatedly move the largest value to the end. In the worst case heap sort takes O(n log n) while bubble sort takes O(n²), so heap sort scales better on large inputs.

At a glance

Property	Bubble sort	Heap sort
Technique	Swap neighbors that are out of order	Build a max-heap in the array, then repeatedly move the largest value to the end
Best case time	O(n)	O(n log n)
Average case time	O(n²)	O(n log n)
Worst case time	O(n²)	O(n log n)
Extra space	O(1)	O(1)
Stable (equal values keep their order)	Yes	No
In place (no extra array)	Yes	Yes
Needs sorted input	No	No

Choose bubble sort when

you want the simplest sort to explain, on tiny or almost sorted data.

Avoid it when

the data is large.

Choose heap sort when

you need a guaranteed O(n log n) time and almost no extra memory.

Avoid it when

you need a stable sort, or the fastest sort on typical data.

The same inputs, counted

These numbers come from running both real implementations: operations (comparisons plus writes, a swap counting as two writes).

Input	Bubble sort	Heap sort
Mixed	40	43
Already sorted	6	53
Reversed	63	40
Nearly sorted	13	50
Duplicates	47	36

Bubble sort vs Heap sort

At a glance

Choose bubble sort when

Avoid it when

Choose heap sort when

Avoid it when

The same inputs, counted

See them run

More comparisons

Bubble sort vs Heap sort

At a glance

When to choose each

Choose bubble sort when

Avoid it when

Choose heap sort when

Avoid it when

The same inputs, counted

See them run

More comparisons