Printing Unique numbers List in C

CONTRIBUTORS.md

@@ -365,3 +365,9 @@ Name: [BenjaminUrquhart](https://github.com/BenjaminUrquhart)<br>
 Coding Experience: Discord Bot Developer (Java) + misc. wrappers. <br>
 Programming Languages: Python 2/3, Java 8<br>
 Email: [email protected]
+
+Name: [rishitc](https://github.com/rishitc)<br>
+Place: India </br>
+Coding Experience: Student <br>
+Programming Languages: C, Python 3, JavaScript<br>
+Email: [email protected]

c/unique numbers/rishitc_unique_numbers.c

@@ -0,0 +1,89 @@
+#include<stdio.h>
+#include<stdlib.h>
+
+typedef struct node {
+    int data;
+    struct node *next;
+}node;
+
+node* createNode(int);
+node* createList(int);
+void display(node*);
+void destroy(node**);
+void insertOrder(int, node**);
+int presenceOf(int, node*);
+
+int main() {
+    node *head = NULL;
+    int len;
+
+    printf("The number of elements in the list:\n");
+    scanf("%d", &len);
+    if(!len) {printf("No elements to input, Exiting...\n"); return 0;}
+    else if(len < 0) {printf("Cannot input %d many elements, Exiting...\n", len); return 0;}
+    printf("Enter the elements of the list:\n");
+    head = createList(len);
+
+    printf("The list after removing duplicates is:\n");
+    display(head);
+
+    destroy(&head);
+    return 0;
+}
+
+void destroy(node** head) {
+    for(node *temp; *head != NULL; temp = (*head), (*head) = (*head) -> next, free(temp));
+}
+
+void display(node* temp) {
+    for(; temp != NULL; printf("%d ", temp -> data), temp = temp -> next);
+}
+node* createNode(int data) {
+    node *temp = calloc(1, sizeof(node));
+    temp -> data = data;
+    return temp;
+}
+
+node* createList(int len) {
+    node *temp = NULL;
+
+    for(int i = 0, num; i < len; ++i) {
+        scanf("%d", &num);
+        presenceOf(num, temp) ?: insertOrder(num, &temp);
+    }
+
+    return temp;
+}
+
+void insertOrder(int data, node** head) {
+    node *temp = createNode(data);
+
+    // no elements in ordered linked list
+    if(!head) {
+        *head = temp;
+        return;
+    }
+    // One or more elements in ordered linked list
+    else {
+        node *t, *prev;
+        for(t = *head, prev = NULL; t != NULL && t -> data < data; prev = t, t = t -> next);
+        if(!prev) { // insert as first node of ordered linked list
+            temp -> next = *head;
+            (*head) = temp;
+        }
+        else if(!t) { // last node of ordered linked list
+            prev -> next = temp;
+        }
+        else { // insert somewhere in between the ordered linked list
+            prev -> next = temp;
+            temp -> next = t;
+        }
+    }
+}
+
+int presenceOf(int num, node* temp) {
+    for(; temp != NULL && temp -> data != num; temp = temp -> next);
+    if(!temp) 
+        return 0;
+    return 1;
+}