DSA · Theory

Insertion Sort Algorithm

Theory

49/810

Insertion Sort Algorithm

Insertion Sort Algorithm is a DSA topic. In plain words you use it for names A→Z in the roll list. Don’t start with a slogan — start with that picture.

Smallest example: n log n vs n². Type it, run it, and say what you see. If you can do that from memory, you know Insertion Sort Algorithm.

From the example next to this theory: Insertion Sort Algorithm — insertion sort grows a sorted prefix by placing each next item correctly.

Trap — unstable sort when equal keys matter. Fix that before you talk about advanced DSA.

Viva — what is Insertion Sort Algorithm? Then show n log n vs n². Then name the trap.

Exam tip

What is Insertion Sort Algorithm? Show this: n log n vs n². Trap: unstable sort when equal keys matter.

Example

def insertion_sort(arr):
    a = arr[:]
    for i in range(1, len(a)):
        key = a[i]
        j = i - 1
        while j >= 0 and a[j] > key:
            a[j + 1] = a[j]
            j -= 1
        a[j + 1] = key
    return a

print(insertion_sort([5, 1, 4, 2]))

Insertion Sort Algorithm — insertion sort grows a sorted prefix by placing each next item correctly.

Short notes

DefInsertion Sort Algorithm — names A→Z in the roll list.
Rulen log n vs n²
Trapunstable sort when equal keys matter
Usethe roll list

DSA · Theory

Insertion Sort Algorithm

← All stacks

Theory

49/810

Insertion Sort Algorithm

Insertion Sort Algorithm is a DSA topic. In plain words you use it for names A→Z in the roll list. Don’t start with a slogan — start with that picture.

Smallest example: n log n vs n². Type it, run it, and say what you see. If you can do that from memory, you know Insertion Sort Algorithm.

From the example next to this theory: Insertion Sort Algorithm — insertion sort grows a sorted prefix by placing each next item correctly.

Trap — unstable sort when equal keys matter. Fix that before you talk about advanced DSA.

Viva — what is Insertion Sort Algorithm? Then show n log n vs n². Then name the trap.

Exam tip

What is Insertion Sort Algorithm? Show this: n log n vs n². Trap: unstable sort when equal keys matter.

Example

def insertion_sort(arr):
    a = arr[:]
    for i in range(1, len(a)):
        key = a[i]
        j = i - 1
        while j >= 0 and a[j] > key:
            a[j + 1] = a[j]
            j -= 1
        a[j + 1] = key
    return a

print(insertion_sort([5, 1, 4, 2]))

Insertion Sort Algorithm — insertion sort grows a sorted prefix by placing each next item correctly.

Short notes

DefInsertion Sort Algorithm — names A→Z in the roll list.
Rulen log n vs n²
Trapunstable sort when equal keys matter
Usethe roll list

Insertion Sort Algorithm

Example

Short notes

Questions

Insertion Sort Algorithm

Example

Short notes

Questions