CA 17 - Write a blog on different sorting methodologies

1. BUBBLE SORT
Repeatedly compare adjacent elements and swap if they are in wrong order. Biggest element “bubbles” to the end each pass.

Steps

• Start from index 0
• Compare arr[j] and arr[j+1]
• Swap if left > right
• Continue till end
• Repeat for n passes

def bubble_sort(arr):
    n = len(arr)
    for i in range(n):
        for j in range(n - i - 1):
            if arr[j] > arr[j + 1]:
                arr[j], arr[j + 1] = arr[j + 1], arr[j]

2. SELECTION SORT
Find the smallest element and place it at the correct position.

Steps

• Assume first element is minimum
• Check rest of array
• Find actual minimum
• Swap with first
• Move to next position

def selection_sort(arr):
    n = len(arr)
    for i in range(n):
        min_idx = i
        for j in range(i + 1, n):
            if arr[j] < arr[min_idx]:
                min_idx = j
        arr[i], arr[min_idx] = arr[min_idx], arr[i]

3. INSERTION SORT
Build sorted array one element at a time, like arranging cards.

Steps

• Start from index 1
• Take current element
• Compare with left side
• Shift bigger elements right
• Insert at correct position

def insertion_sort(arr):
    for i in range(1, len(arr)):
        key = arr[i]
        j = i - 1

        while j >= 0 and arr[j] > key:
            arr[j + 1] = arr[j]
            j -= 1

        arr[j + 1] = key

4. MERGE SORT
Divide array into halves → sort them → merge back

StepS

• Divide array into 2 halves
• Recursively sort both halves
• Merge sorted halves
• Repeat until fully sorted

def merge_sort(arr):
    if len(arr) <= 1:
        return arr

    mid = len(arr) // 2
    left = merge_sort(arr[:mid])
    right = merge_sort(arr[mid:])

    return merge(left, right)

def merge(left, right):
    result = []
    i = j = 0

    while i < len(left) and j < len(right):
        if left[i] < right[j]:
            result.append(left[i])
            i += 1
        else:
            result.append(right[j])
            j += 1

    result.extend(left[i:])
    result.extend(right[j:])
    return result