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sllist.c
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sllist.c
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/**
* This file contains the definitions for all the functions for performing certain rudimentary list operations.
* @file sllist.c
* @author Sourabh Warrier
* @date Saturday December 16th, 2023
*/
#include <stdio.h>
#include <stdlib.h>
#include "sllist.h"
/**
* Displays the contents of a list
* @param Node* head : pointer to a node, usually the head node of a list.
* @return void
*/
void display(Node* head){
Node* current = head;
int index = 0;
while(current != NULL){
printf("[%d]:%d -> ",index++,current->value);
current = current->next;
}
if (current == NULL){
printf("NULL\n");
}
return;
}
/**
* Attach a node with a new value to the beginning of a list. This node becomes the new head.
* @param Node* head : pointer to the head node of a list
* @param int new_value : value to be attached
* @return (Node*) pointer to the head node
*/
Node* attach(Node* head, int new_value){
Node* new_node = calloc(1,sizeof(Node));
new_node->value = new_value;
if (head != NULL){
new_node->next = head;
}
return new_node;
}
/**
* Append a node with a new value to the end of a list.
* @param Node* head : pointer to the head node of a list
* @param int new_value : value to be appended
* @return (Node*) pointer to the head node
*/
Node* append(Node* head, int new_value){
Node* new_node = calloc(1,sizeof(Node));
new_node->value = new_value;
if (head == NULL){
head = new_node;
}
else{
Node* current = head;
while(current->next != NULL){
current = current->next;
}
current->next = new_node;
}
return head;
}
/**
* Remove the head node from a list. The next node in the list becomes the new head.
* @param Node* head : pointer to the head of a list
* @return (Node*) pointer to the next node in the list or a NULL pointer in the case of a singleton or empty list
*/
Node* drop_head(Node* head){
if (head != NULL){
Node* head_prev = head;
head = head->next;
free(head_prev);
}
return head;
}
/**
* Remove the last node in a list.
* @param Node* head : pointer to the head node of a list
* @return (Node*) pointer to the head node
*/
Node* drop_tail(Node* head){
if(head == NULL){
return head;
}
else if(head->next == NULL){
free(head);
return NULL;
}
else{
Node* current = head;
Node* node_prev;
while(current->next != NULL){
node_prev = current;
current = current->next;
}
free(current);
node_prev->next = NULL;
}
return head;
}
/**
* Obtain the length of a list.
* @param Node* head : pointer to the head node of a list
* @return (int) length of the list
*/
int length(Node* head){
int len = 0;
Node* current = head;
while(current != NULL){
len++;
current = current->next;
}
return len;
}
/**
* Determine whether a node with a given value is present in the list.
* @param Node* head : pointer to the head node of a list
* @param int target : value to find
* @return (int) 1 if present, 0 otherwise
*/
int present(Node* head, int target){
int found = 0;
Node* current = head;
while(current != NULL){
if (current->value == target){
found = 1;
break;
}
current = current->next;
}
return found;
}
/**
* Count the number occurrences of nodes with a given value in the list
* @param Node* head : pointer to the head node of a list
* @param int target : value whose occurrences to count
* @return (int) number of occurrences
*/
int count(Node* head, int target){
int count = 0;
Node* current = head;
while(current != NULL){
if (current->value == target){
count++;
}
current = current->next;
}
return count;
}
/**
* Replace first n nodes of a given value with a new value. The number of replacements is specified by the parameter ttl.
* @param Node* head : pointer to the head node of a list
* @param int target : value that is to be replaced
* @param int new_value : new value
* @param int ttl : maximum number of replacements to be made
* @return void
*/
void replace(Node* head, int target, int new_value, int ttl){
int flag = (ttl > 0);
Node* current = head;
while(current != NULL){
if ((flag && ttl) || !flag){
if (current->value == target){
current->value = new_value;
ttl--;
}
}
current = current->next;
}
return;
}
/**
* Remove the first n nodes that match a given value.
* @param Node* head : pointer to the head node of a list
* @param int target : value to be matched and removed
* @param int ttl : maximum of number of removals to be made
* @return (Node*) pointer to the head node
*/
Node* drop_match(Node* head, int target, int ttl){
int flag = (ttl > 0);
Node* current = head;
Node* node_prev;
if(current == NULL){
return current;
}
else if(current->next == NULL){
if ((flag && ttl) || !flag){
if(current->value == target){
free(current);
return NULL;
}
}
}
else{
while(current != NULL){
if ((flag && ttl) || !flag){
if (current->value == target){
if(node_prev == NULL){
head = head->next;
free(current);
current = head;
ttl--;
}
else{
node_prev->next = current->next;
free(current);
current = node_prev->next;
ttl--;
}
}
else{
node_prev = current;
current = current->next;
}
}
else{
break;
}
}
}
return head;
}
/**
* Join two lists by appending the head of the second list to the tail of the first.
* @param Node* head1 : pointer to the head node of the first list
* @param Node* head2 : pointer to the head node of the second list
* @return (Node*) pointer to the head node
*/
Node* join(Node* head1, Node* head2){
if(head1 == NULL){
return head2;
}
else if(head2 == NULL){
return head1;
}
else{
Node* current = head1;
while(current->next!=NULL){
current = current->next;
}
current->next = head2;
}
return head1;
}
/**
* Reverse the first n nodes in a list
* @param Node* head : pointer to the head node of a list
* @param int ttl : length of initial n-node segment to be reversed
* @return (Node*) pointer to the head node
*/
Node* reverse(Node* head, int ttl){
int flag = (ttl > 0);
Node* current = head;
if (ttl == 1 || current == NULL || current->next == NULL){
return current;
}
Node* node_prev = NULL;
Node* node_next = NULL;
while(current->next != NULL){
if ((flag && ttl>1) || !flag){
node_next = current->next;
if(node_prev !=NULL){
current->next = node_prev;
}
node_prev = current;
current = node_next;
ttl--;
}
else{
break;
}
}
head->next = current->next;
current->next = node_prev;
return current;
}
/**
* Sort the nodes in a list by value in ascending order.
* @param Node* head : pointer to the head node of a list
* @return void
*/
void sort(Node* head){ //BUBBLE SORT
if (head == NULL){
return;
}
Node* current;
int temp;
int swapped = 1;
do{
current = head;
swapped = 0;
while(current->next != NULL){
if(current->value>current->next->value){
temp = current->value;
current->value = current->next->value;
current->next->value = temp;
swapped = 1;
}
current = current->next;
}
}while(swapped);
return;
}
/**
* Remove duplicate nodes in a list, retaining a given number of copies.
* @param Node* head : pointer to the head node of a list
* @param int max_duplicates : maximum number of copies to retain
* @return void
*/
void drop_duplicates(Node* head, int max_duplicates){
int flag = (max_duplicates > 0);
Node* current = head;
Node* node_prev;
int duplicate_counter;
while(current!= NULL && current->next != NULL){
duplicate_counter = max_duplicates;
node_prev = current;
Node* node_next = current->next;
while(node_next != NULL){
if(current->value == node_next->value){
if((flag && duplicate_counter==0) || !flag){
node_prev->next = node_next->next;
free(node_next);
}
else{
node_prev = node_next;
duplicate_counter--;
}
node_next = node_prev->next;
}
else{
node_prev = node_next;
node_next = node_next->next;
}
}
current = current->next;
}
return;
}
/**
* Delete a list from memory.
* @param Node* head : pointer to the head node of a list
* @return void
*/
void del(Node* head){
Node* current = head;
while(head != NULL){
current = head;
head=head->next;
free(current);
}
return;
}
/**
* Insert a node with a new value after the first occurrence of a node with a given value.
* @param Node* head : pointer to the head node of a list
* @param int target : value after whose first occurrence a new node is to be inserted
* @param int new_value : value of the new node to be inserted
* @return (Node*) pointer to the head node
*/
Node* insert_after(Node* head, int target, int new_value){
Node* new_node = (Node*)calloc(1, sizeof(Node));
Node* current = head;
Node* temp;
new_node->value = new_value;
int inserted = 0;
while(current != NULL){
if(current->value == target){
temp = current->next;
current->next = new_node;
new_node->next = temp;
inserted = 1;
break;
}
current = current->next;
}
if (!inserted){
printf("Value %d was not inserted : expected predecessor %d not found\n", new_value, target);
free(new_node);
}
return head;
}