// C program to segregate even and odd nodes in a
// Linked List
#include <stdio.h>
#include <stdlib.h>
/* a node of the singly linked list */
struct Node
{
int data;
struct Node *next;
};
void segregateEvenOdd(struct Node **head_ref)
{
struct Node *end = *head_ref;
struct Node *prev = NULL;
struct Node *curr = *head_ref;
/* Get pointer to the last node */
while (end->next != NULL)
end = end->next;
struct Node *new_end = end;
/* Consider all odd nodes before the first even node
and move then after end */
while (curr->data %2 != 0 && curr != end)
{
new_end->next = curr;
curr = curr->next;
new_end->next->next = NULL;
new_end = new_end->next;
}
// 10->8->17->17->15
/* Do following steps only if there is any even node */
if (curr->data%2 == 0)
{
/* Change the head pointer to point to first even node */
*head_ref = curr;
/* now current points to the first even node */
while (curr != end)
{
if ( (curr->data)%2 == 0 )
{
prev = curr;
curr = curr->next;
}
else
{
/* break the link between prev and current */
prev->next = curr->next;
/* Make next of curr as NULL */
curr->next = NULL;
/* Move curr to end */
new_end->next = curr;
/* make curr as new end of list */
new_end = curr;
/* Update current pointer to next of the moved node */
curr = prev->next;
}
}
}
/* We must have prev set before executing lines following this
statement */
else prev = curr;
/* If there are more than 1 odd nodes and end of original list is
odd then move this node to end to maintain same order of odd
numbers in modified list */
if (new_end!=end && (end->data)%2 != 0)
{
prev->next = end->next;
end->next = NULL;
new_end->next = end;
}
return;
}
/* UTILITY FUNCTIONS */
/* Function to insert a node at the beginning */
void push(struct Node** head_ref, int new_data)
{
/* allocate node */
struct Node* new_node =
(struct Node*) malloc(sizeof(struct Node));
/* put in the data */
new_node->data = new_data;
/* link the old list off the new node */
new_node->next = (*head_ref);
/* move the head to point to the new node */
(*head_ref) = new_node;
}
/* Function to print nodes in a given linked list */
void printList(struct Node *node)
{
while (node!=NULL)
{
printf("%d ", node->data);
node = node->next;
}
}
/* Driver program to test above functions*/
int main()
{
/* Start with the empty list */
struct Node* head = NULL;
/* Let us create a sample linked list as following
0->2->4->6->8->10->11 */
push(&head,88 );
push(&head, 6);
push(&head, 7);
push(&head, 8);
push(&head, 9);
push(&head, 10);
push(&head, 11);
printf("\nOriginal Linked list \n");
printList(head);
segregateEvenOdd(&head);
printf("\nModified Linked list \n");
printList(head);
return 0;
}
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C language is one of the most popular general-purpose programming language developed by Dennis Ritchie at Bell laboratories for UNIX operating system. The initial release of C Language was in the year 1972. Most of the desktop operating systems are written in C Language.
When ever you want to perform a set of operations based on a condition if-else is used.
if(conditional-expression) {
// code
} else {
// code
}
You can also use if-else for nested Ifs and if-else-if ladder when multiple conditions are to be performed on a single variable.
Switch is an alternative to if-else-if ladder.
switch(conditional-expression) {
case value1:
// code
break; // optional
case value2:
// code
break; // optional
...
default:
// code to be executed when all the above cases are not matched;
}
For loop is used to iterate a set of statements based on a condition.
for(Initialization; Condition; Increment/decrement){
// code
}
While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.
while(condition) {
// code
}
Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.
do {
// code
} while (condition);
Array is a collection of similar data which is stored in continuous memory addresses. Array values can be fetched using index. Index starts from 0 to size-1.
data-type array-name[size];
data-type array-name[size][size];
Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity.
Two types of functions are present in C
Library functions are the in-built functions which are declared in header files like printf(),scanf(),puts(),gets() etc.,
User defined functions are the ones which are written by the programmer based on the requirement.
return_type function_name(parameters);
function_name (parameters)
return_type function_name(parameters) {
//code
}