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Program for n’th node from the end of a Linked List in C program
Given with n nodes the task is to print the nth node from the end of a linked list. The program must not change the order of nodes in a list instead it should only print the nth node from the last of a linked list.
Example
Input -: 10 20 30 40 50 60 N=3 Output -: 40
In the above example, starting from first node the nodes till count-n nodes are traversed i.e 10,20 30,40, 50,60 and so the third node from the last is 40.
Instead of traversing the entire list this efficient approach can be followed −
- Take a temporary pointer, let’s say, temp of type node
- Set this temp pointer to first node which is pointed by head pointer
- Set counter to the number of nodes in a list
- Move temp to temp → next till count-n
- Display temp → data
If we use this approach, than count will be 5 and program will iterate the loop till 5-3 i.e. 2, so starting from 10 on 0th location than to 20 on 1st location and 30 on 2nd location which is the result. So by this approach there is no need to traverse the entire list till end which will save space and memory.
Algorithm
Start Step 1 -> create structure of a node and temp, next and head as pointer to a structure node struct node int data struct node *next, *head, *temp End Step 2 -> declare function to insert a node in a list void insert(int val) struct node* newnode = (struct node*)malloc(sizeof(struct node)) newnode->data = val IF head= NULL set head = newnode set head->next = NULL End Else Set temp=head Loop While temp->next!=NULL Set temp=temp->next End Set newnode->next=NULL Set temp->next=newnode End Step 3 -> Declare a function to display list void display() IF head=NULL Print no node End Else Set temp=head Loop While temp!=NULL Print temp->data Set temp=temp->next End End Step 4 -> declare a function to find nth node from last of a linked list void last(int n) declare int product=1, i Set temp=head Loop For i=0 and i<count-n and i++ Set temp=temp->next End Print temp->data Step 5 -> in main() Create nodes using struct node* head = NULL Declare variable n as nth to 3 Call function insert(10) to insert a node Call display() to display the list Call last(n) to find nth node from last of a list Stop
Example
#include<stdio.h>
#include<stdlib.h>
//structure of a node
struct node{
int data;
struct node *next;
}*head,*temp;
int count=0;
//function for inserting nodes into a list
void insert(int val){
struct node* newnode = (struct node*)malloc(sizeof(struct node));
newnode->data = val;
newnode->next = NULL;
if(head == NULL){
head = newnode;
temp = head;
count++;
} else {
temp->next=newnode;
temp=temp->next;
count++;
}
}
//function for displaying a list
void display(){
if(head==NULL)
printf("no node ");
else {
temp=head;
while(temp!=NULL) {
printf("%d ",temp->data);
temp=temp->next;
}
}
}
//function for finding 3rd node from the last of a linked list
void last(int n){
int i;
temp=head;
for(i=0;i<count-n;i++){
temp=temp->next;
}
printf("
%drd node from the end of linked list is : %d" ,n,temp->data);
}
int main(){
//creating list
struct node* head = NULL;
int n=3;
//inserting elements into a list
insert(1);
insert(2);
insert(3);
insert(4);
insert(5);
insert(6);
//displaying the list
printf("
linked list is : ");
display();
//calling function for finding nth element in a list from last
last(n);
return 0;
}Output
linked list is : 1 2 3 4 5 6 3rd node from the end of linked list is : 4
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