Sorting

SORTING ALGORITHM IN C-

BUBBLE SORT AND SELECTION SORT

Contents

Introduction to Sorting

Bubble Sort

Selection Sort

Advantages

Disadvantages

Summary

Introduction To Sorting Sorting is a process in which records are arranged in

ascending or descending order.

Example: Telephone directory.

Sorting

• Sorting takes an unordered collection and makes it an ordered one.

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BUBBLE SORTOldest, most easiest, straightforward and simplistic

method of sorting data.

Procedure: In this technique, the two successive elements A[i] and A[i+1] are exchanged whenever A[i] >= A[i+1].

Bubble Sort Algorithmfor(i=1;i<n;i++){

for(j=0;j<n-i;j++){if(a[j]>=a[j+1]){exchange (a[j],a[j+1])}}

}

BUBBLE SORT“Bubbling Up" the Largest Element

• Traverse a collection of elements–Move from the front to the end– “Bubble” the largest value to the end using pair-

wise comparisons and swapping

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"Bubbling Up" the Largest Element

• Traverse a collection of elements–Move from the front to the end– “Bubble” the largest value to the end using pair-

wise comparisons and swapping

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1 2 3 4 5 6Swap42 77

"Bubbling Up" the Largest Element

• Traverse a collection of elements–Move from the front to the end– “Bubble” the largest value to the end using pair-

wise comparisons and swapping

512357742 101

1 2 3 4 5 6Swap35 77

"Bubbling Up" the Largest Element

• Traverse a collection of elements–Move from the front to the end– “Bubble” the largest value to the end using pair-

wise comparisons and swapping

512773542 101

1 2 3 4 5 6Swap12 77

"Bubbling Up" the Largest Element

• Traverse a collection of elements–Move from the front to the end– “Bubble” the largest value to the end using pair-

wise comparisons and swapping

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No need to swap

"Bubbling Up" the Largest Element

• Traverse a collection of elements–Move from the front to the end– “Bubble” the largest value to the end using pair-

wise comparisons and swapping

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1 2 3 4 5 6Swap5 101

"Bubbling Up" the Largest Element

• Traverse a collection of elements–Move from the front to the end– “Bubble” the largest value to the end using pair-

wise comparisons and swapping

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Largest value correctly placed

Items of Interest

• Notice that only the largest value is correctly placed

• All other values are still out of order• So we need to repeat this process

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Largest value correctly placed

Repeat “Bubble Up” How Many Times?

• If we have N elements…

• And if each time we bubble an element, we place it in its correct location…

• Then we repeat the “bubble up” process N – 1 times.

“Bubbling” All the Elements

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N -

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Advantages & Disadvantages of Bubble Sort

Advantages:very simple easy to program can be implemented in a short amount of time preferable when short lists are used.

Disadvantages: runs slowly and hence it is not efficient. Even if the elements are sorted, n-1 passes are required

to sort.

Selection SortSelection sort determines the minimum (or maximum) of

the list and swaps it with the element at the index where it is supposed to be.

Procedure : In this technique after obtaining the smallest element, it should be exchanged with the element in the ith position. temp = A[pos];A[pos] = A[i];A[i] = temp;

Selection Sort Algorithmfor(i=0;i<n-1;i++){ pos=i

for(j=i+1;j<n;j++){if(a[j]<a[pos])pos=j}temp=a[pos]a[pos]=a[i]a[i]=temp

}

Selection Sort

• Traverse a collection of elements• It works by first finding the smallest element using a

linear scan and swapping it into the first position in the list.

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Selection Sort

• Traverse a collection of elements• Finding the first smallest element by scanning the

remaining elements

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Selection Sort

• Traverse a collection of elements• Finding the second smallest element by scanning the

remaining elements, and so on....

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Selection Sort

• Traverse a collection of elements

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Selection Sort

• Traverse a collection of elements

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Selection Sort

• Traverse a collection of elements

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Selection Sort

• Traverse a collection of elements

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Advantages & Disadvantages of Selection Sort

Advantages: Better to use when sorting through arrays. Performance is quicker than Bubble sort. Notable for its programming The simplest of sorting techniques and works very well for

small files

Disadvantages: Quite inefficient for sorting large data volumes. Spends most of its time trying to find the minimum

element in the "unsorted" part of the array.

SummaryThe choice of a sort algorithm normally bases on

some properties of the data you have to sort. Bubble sort is not a practical sorting algorithm

when n is large.Selection sort algorithm is an easy-to-program,

but very inefficient sorting algorithm.

References [1] Ashok N. Kamthane, Introduction to Data

Structures in C, Pearson Education, India, 2007 [2] A. M. Padma Reddy, Systematic Approach to Data

Structures Using C, 7th Edition, 2007 [3] Ellis Horowitz, Fundamentals of Computer

Algorithms, Universities Press, 2nd Edition, 2009

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