Thursday, December 1, 2011

Data Structure: Implementing Bubble Sort using C/C++

In Bubble sort, each pass consists of comparison each element in the file with its successor (i.e. x[i] with x[i+1]) and interchanging two elements if they are not in the proper order.

Example: Let us consider following array of elements

16

52 42 35 8

Following comparison are make on the first pass

x[0] with x[1] (16 with 52) No interchange
x[1] with x[2] (52 with 42) Interchange
x[2] with x[3] (52 with 35) Interchange

Thus after first pass, we can get: 16      42     35       8       52

  • Note that after first pass, largest element (i.e. 52) get its proper position
  • In general, x[n-1] will be in its proper position after iteration 1

We can list completer iterations as follows:

Iteration 0:       16          52         42               35                8
Iteration 1:       16          42         35               8                 52
Iteration 2:       16          35         8                42                52
Iteration 3:       16          8          35               42                52
Iteration 4:        8          16         35               42                52

Hence, for ith iteration, n-i iteration is required.

Algorithm

1. Declare and initialize necessary variable such as number of data items n, array, i, j etc
2. For i = 0 to i < (n - i), repeat step 3 to 4
3. For j = 0 to j < (n-i-1), repeat step 4
4. If x[j] > x[j+1] then swap the element as
temp = x[j]
x[j] = x[j+1]
x[j+1] = temp
5. Display the sorted array



Source code for Bubble Sort

#include<iostream>
using namespace std;
class BubbleSort{
    private:
        int no_of_elements;
        int elements[10];
    public:
        void getarray();
        void sortit();
        void display();
};
void BubbleSort::getarray(){
    cout<<"How many elements?: ";
    cin>>no_of_elements;
    cout<<"Insert array of element to sort: ";
    for(int i=0;i<no_of_elements;i++){
        cin>>elements[i];
    }
}
void BubbleSort::sortit(){
    int temp;
    for(int i = 0; i < no_of_elements; i++){
        for(int j =0; j < no_of_elements - 1 - i; j++){
            if(elements[j] > elements[j+1]){
                temp = elements[j];
                elements[j] = elements[j+1];
                elements[j+1] = temp;
            }
        }
    }
}
void BubbleSort::display(){
    cout<<"The sorted element is\n";
    for(int i = 0 ; i < no_of_elements; i++){
        cout<<elements[i]<<" ";
    }
}
int main(){
    BubbleSort BS;
    BS.getarray();
    BS.sortit();
    BS.display();
    return 0;
}

Efficiency of Bubble Sort:



The number of comparison between n elements is equal to (n-1) and total number of passes is also (n-1), The total number of comparison are therefore (n-1) * (n-1). Hence the efficiency of bubble sort is O(n^2)

1 comment:

  1. ahhh thankyou for this artical sir , i need that one :)

    ReplyDelete