Added linked list data structure example

algorithms/data-structures/linked_list.c

@@ -0,0 +1,100 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+/*
+This program is example of linked list.
+by : https://github.com/powerpizza
+
+Fact about C-lang pointers :-
+if function takes structure as argument like : add_data(Node * n, int data)
+so n = ____ will not gonna affect actual structure.
+but *n = ____ will gonna affect actual structure.
+
+but n->member1 = ____ will gonna affect and change value of actual structure's member.
+*/
+
+typedef struct node{
+    int data;
+    struct node * next_node;
+} Node;
+
+Node * initLinkedList(int value){
+    // To create/initialize a new linked list.
+    Node * node1 = (Node*) malloc(sizeof(Node));
+    node1->data = value;
+    node1->next_node = NULL;
+    return node1;
+}
+
+void addElement(Node * n, int data){
+    // To add new element at the end of list
+    while (n->next_node != NULL)
+    {
+        n = n->next_node;
+    }
+    n->data = data;
+    Node * to_add = (Node*)malloc(1*sizeof(Node));
+    to_add->data = 0;
+    to_add->next_node = NULL;
+    n->next_node = to_add;
+}
+
+void printList(Node * n){
+    // To print whole content of linked list.
+    while (n->next_node != NULL)
+    {
+        printf("%d\n", n->data);
+        n = n->next_node;
+    }
+}
+
+int getListLength(Node * n){
+    // To get no. of items in linked list.
+    int i = 0;
+    while (n->next_node != NULL)
+    {
+        i++;
+        n = n->next_node;
+    }
+    return i;
+}
+
+void insertAtIndex(Node * n, int idx_, int value){
+    // To insert a new node in linked list at any index.
+    for (int i = 0; i < idx_; i++){
+        n = n->next_node;
+    }
+    Node * new_data = (Node*) malloc(sizeof(Node));
+    new_data->data = n->data;
+    new_data->next_node = n->next_node;
+    n->data = value;
+    n->next_node = new_data;
+}
+
+void deleteByIndex(Node * n, int idx_){
+    // To delete any index node from linked list
+    for (int i = 0; i < idx_; i++){
+        n = n->next_node;
+    }
+    n->data = n->next_node->data;
+    n->next_node = n->next_node->next_node;
+}
+
+int main(){
+    // USAGE....
+    Node * l1 = initLinkedList(100);
+    addElement(l1, 30);
+    addElement(l1, 40);
+    // printList(&l1);
+    // printf("LENGTH OF LINKED LIST IS : %d\n", getListLength(&l1));
+    addElement(l1, 40);
+    addElement(l1, 90);
+    // printf("LENGTH OF LINKED LIST IS : %d\n", getListLength(&l1));
+    printList(l1);
+    // printf("AFTER INSERTION\n");
+    // insertAtIndex(l1, 4, 100);
+    printf("AFTER DELETION\n");
+    deleteByIndex(l1, 3);
+    printList(l1);
+    return 0;
+}