# C++ Program For Bubble Sort

Problem :- Write A C++ Program For Bubble Sort Using Array

Logic :- Step-By-Step Example .

Let us take the array of numbers "5 1 4 2 8", and sort the array from lowest number to greatest number using bubble sort. In each step, elements written in bold are being compared. Three passes will be required.

First Pass

( 5 1 4 2 8 ) to ( 1 5 4 2 8 ), Here, algorithm compares the first two elements, and swaps since 5 > 1.   ( 1 5 4 2 8 ) to ( 1 4 5 2 8 ), Swap since 5 > 4 ( 1 4 5 2 8 ) to ( 1 4 2 5 8 ), Swap since 5 > 2
( 1 4 2 5 8 ) to ( 1 4 2 5 8 ), Now, since these elements are already in order (8 > 5), algorithm does not swap them.

Second Pass
( 1 4 2 5 8 ) to  ( 1 4 2 5 8 )
( 1 4 2 5 8 ) to  ( 1 2 4 5 8 ), Swap since 4 > 2
( 1 2 4 5 8 ) to  ( 1 2 4 5 8 )
( 1 2 4 5 8 ) to  ( 1 2 4 5 8 )
Now, the array is already sorted, but the algorithm does not know if it is completed. The algorithm needs one whole pass without any swap to know it is sorted.

Third Pass
( 1 2 4 5 8 ) to  ( 1 2 4 5 8 )
( 1 2 4 5 8 ) to  ( 1 2 4 5 8 )
( 1 2 4 5 8 ) to  ( 1 2 4 5 8 )
( 1 2 4 5 8 ) to  ( 1 2 4 5 8 )

Complexity :-

Best-Case --> O(n)
Average-Case-->O(n^2)
Worst-Case-->O(n^2)
Worst-case space complexity-->O(1)  auxiliary

Note :- Bubble Sort Complexity O(n^2) in All Cases But if All Element in An Array is Already Sorted the We put a Special Condition if All Element Are Sorted then No Further Iteration And Loop Stop .

See How Bubble Sort Works .

source-Wikipedia

This is a Extended Version of Bubble Sort You can Also Edit For Minimum Iteration Try By Own .

Try This C++ Program For Selection Sort

Solution :-

#include<iostream>

#include<stdlib.h>

using namespace std;

int main()

{

int a[100],i,s,j,temp,nochanges;
cout<<"ENTER THE SIZE OF ARRAY : "<<endl;
cin>>s;
cout<<"Enter The Elememnt In Array \n"<<endl;
for(i=0;i<s;i++)
{
cin>>a[i];
}
for(i=0;i<s;++i)
{
nochanges=0;
for(j=0;j<(s-1);++j)
{
if(a[j]>a[j+1])
{
temp = a[j];
a[j] = a[j+1];
a[j+1] = temp;
nochanges++;
}

}
if(nochanges==0)
break;
}
cout<<"\nSorted Array In Accending Order \n"<<endl;

for(i=0;i<s;i++)
{
cout<<a[i]<<" ";
}
cout<<"\n\nSorted Array In Decending Order \n"<<endl;

for(i=s-1;i>=0;i--)
{
cout<<a[i]<<" ";
}
return 0;
}

Output:-

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#### post written by: Ghanendra Yadav

Hi, I’m Ghanendra Yadav, SEO Expert, Professional Blogger, Programmer, and UI Developer. Get a Solution of More Than 500+ Programming Problems, and Practice All Programs in C, C++, and Java Languages. Get a Competitive Website Solution also Ie. Hackerrank Solutions and Geeksforgeeks Solutions. If You Are Interested to Learn a C Programming Language and You Don't Have Experience in Any Programming, You Should Start with a C Programming Language, Read: List of Format Specifiers in C.