C++ Program to Implement Selection Sort

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This is a C++ program to sort the given data using Selection Sort.

Problem Description

1. Selection sort algorithm sort data by comparing one element to every other element and decide its position.
2. The time complexity of this algorithm is O(n^2).

Problem Solution

1. Starting from the beginning pick one number.
2. Compare it with others one by one.
3. replace if the other number is lesser than this one.
4. Display the result.
5. Exit.

Program/Source Code

C++ program to implement Selection Sort.
This program is successfully run on Dev-C++ using TDM-GCC 4.9.2 MinGW compiler on a Windows system.

#include <iostream>
 
using namespace std;
 
// Sort arr[] of size n using Selection Sort. 
void SelectionSort (int arr[], int n)
{
	int i, j;
	for (i = 0; i < n; ++i)
	{
		for (j = i+1; j < n; ++j)
		{
			// Comparing consecutive data and switching values if value at i > j.
			if (arr[i] > arr[j])
			{
				arr[i] = arr[i]+arr[j];
				arr[j] = arr[i]-arr[j];
				arr[i] = arr[i]-arr[j];
			}	
		}
		// Value at i will be minimum of all the values above this index.
	}	
}	
 
int main()
{
	int n, i;
	cout<<"\nEnter the number of data element to be sorted: ";
	cin>>n;
 
	int arr[n];
	for(i = 0; i < n; i++)
	{
		cout<<"Enter element "<<i+1<<": ";
		cin>>arr[i];
	}
 
	SelectionSort(arr, n);
 
	// Display the sorted data.
	cout<<"\nSorted Data ";
	for (i = 0; i < n; i++)
		cout<<"->"<<arr[i];
 
	return 0;
}
Program Explanation

1. Take input of data.
2. Call SelectionSort() function with ‘arr’ the array of data and ‘n’ the number of values, in the argument list.
3. Implement Sorting algorithm using nested for loop.
4. The first loop will run on ‘i’ from 0 to n-1.
5. The second loop will run on ‘j’ from i+1 to n-1.
6. Compare value at i with value at j.
7. Switch the values if arr[j+1] < arr[j]. 8. Return to main and display the result. 9. Exit.

Runtime Test Cases
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Case 1:(average case)
 
Enter the number of data element to be sorted: 5
Enter element 1: 998
Enter element 2: 451
Enter element 3: 2
Enter element 4: 35
Enter element 5: 1206
 
Sorted Data ->2->35->451->998->1206
 
 
Case 2:(best case)
 
Enter the number of data element to be sorted: 5
Enter element 1: 2
Enter element 2: 332
Enter element 3: 456
Enter element 4: 1024
Enter element 5: 16565
 
Sorted Data ->2->332->456->1024->16565
 
 
case 3: (worst case)
 
Enter the number of data element to be sorted: 5
Enter element 1: 99845
Enter element 2: 564
Enter element 3: 332
Enter element 4: 86
Enter element 5: 1
 
Sorted Data ->1->86->332->564->99845

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To practice all C++ Algorithms, here is complete set of 1000 C++ Algorithms.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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