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## Friday 27 March 2015

### implementation of bubble sort algorithm in C

Implementation of bubble sort algorithm in C

/*
* implementation of bubble sort algorithm in C
* By K Sreram
*/

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>

enum BOOL {FALSE, TRUE};
typedef int BOOL;

struct NODE;
typedef struct NODE Node;
typedef Node* PtrNode;
typedef PtrNode List;
typedef PtrNode Position;
typedef int DataType;

struct NODE{ // single link list node
DataType data;
PtrNode next;
};

PtrNode NewList() // returns the List's header
{
PtrNode tempNode =  malloc(sizeof(Node));
tempNode->next = NULL;
return tempNode;
}
Position NewNode() // creates a new node
{
return malloc(sizeof(Node));
}

void Delete(PtrNode node)// deletes the node
{
free(node);
}
BOOL IsLast(List L, Position pos) // checks id the given position is last in the list
{
return (pos->next == NULL);
}

void Insert ( List L, DataType data, Position pos)// inserts a data field in a particular position
{
Position tempPos;
tempPos = NewNode(); // creates and allocates memory space
if(tempPos == NULL)
{
fprintf(stderr, "error: request for allocation of memory using function \"malloc\" rejected");
return;
}
tempPos->data = data;
tempPos->next = pos->next;
pos->next = tempPos;
}
void DeleteList(List L)
{
PtrNode tempNode = L->next, tempNode2;
while (tempNode != NULL)
{
tempNode2 = tempNode->next;
Delete(tempNode);
tempNode = tempNode2;
}
L->next = NULL;
}
void DisplayElement(DataType element) // displays an individual element
{
printf("%d\n", element);
}
void Display (List L) // this function displays the list's contents linearly
{
Position pos = L->next;
if(pos == NULL)
return;
while (pos != NULL)
{
DisplayElement(pos->data);
pos = pos->next;
}
}
Position FindEnd(List L)
{

Position tempPos=L;
while(!IsLast(L, tempPos))
tempPos = tempPos->next;
return tempPos;
}
void SwapNodePair(PtrNode preNode) // swap the nodes connected to the passed on nodes
{
Position temp = preNode->next;
preNode->next = preNode->next->next;
temp->next = preNode->next->next;
preNode->next->next = temp;
}

void BubbleSort(List L) // this function runs at O(N^2) for the worse case
{
if(L->next == NULL || L->next->next == NULL)
return; // cannot sort 2 or one inputs
Position pos;
Position End = FindEnd(L);
while(End != L->next)
{
pos = L;
while(pos->next->next != End)
{
if(pos->next->data < pos->next->next->data)
SwapNodePair(pos);
pos = pos->next;
}
if(pos->next->data < pos->next->next->data)
SwapNodePair(pos);
End = pos->next;
}
}

int main()
{
List L = NewList(); // creates a new list
int n, i, data;
Position top = L;
printf("enter size of list");
scanf("%d", &n);
if(n < 2 )
{
fprintf(stderr,"invalid list size. The size cannot be lesser than 2");
getch();
return -1;
}
printf("enter elements: ");
for(i=0; i<n; i++)
{
scanf("%d", &data); // creates the list
Insert(L, data, top);
top = top->next;
}
BubbleSort(L);
printf("\nthe sorted elements:\n");
Display(L);
getch();
return 0;
}

copyright (c) 2015 K Sreram.