# Python Program - Bubble Sort

Bubble sort is the simplest sorting algorithm. The Bubble sort is based on the idea that every adjacent elements are compared and swapped if found in wrong order.

### Example:

To understand the bubble sort, lets consider an unsorted array *[1, 23, 10, -2]* and discuss each step taken to sort the array in ascending order. In every pass, two adjacent elements are checked and swapped if found in wrong order.

__First Pass__:*(1)* and *(23)* are compared and found in correct order(ascending order in this case). After that *(23)* and *(10)* are compared, since *(23>10)*, hence these numbers are swapped. Then *(23)* and *(-2)* are compared and swapped.

__Second Pass__:*(1)* and *(10)* are compared and found in correct order. Then *(10)* and *(-2)* are compared, since *(10>-2)*, hence these numbers are swapped. After that *(10)* and *(23)* are compared and found in correct order.

__Third Pass__:*(1)* and *(-2)* are compared, since *(1>-2)*, hence these numbers are swapped. After that *(1,10)* and *(10,23)* are checked and found in correct order.

## Implementation of Bubble Sort

# function for bubble sort def bubblesort(MyList): for i in range(len(MyList)): for j in range(len(MyList)-i-1): if(MyList[j]>MyList[j+1]): MyList[j] , MyList[j+1] = MyList[j+1], MyList[j] # function to print list def PrintList(MyList): for i in MyList: print(i, end=" ") print("\n") # test the code MyList = [1, 10, 23, 50, 4, 9, -4] print("Original List") PrintList(MyList) bubblesort(MyList) print("Sorted List") PrintList(MyList)

The above code will give the following output:

Original List 1 10 23 50 4 9 -4 Sorted List -4 1 4 9 10 23 50

### Time Complexity:

The time complexity of bubble sort is *Θ(N²)* in all cases even if the whole array is sorted because the entire array need to be iterated for every element and it contains two nested loops.