Added C - Queue

Data Structures/Queue/queue.c

@@ -0,0 +1,118 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+//self referencing structure with one data element
+struct Node {
+    int data;
+    struct Node *next;
+};
+
+// Aliasing for easier referencing
+typedef struct Node Node; 
+
+/*-------------------------------------- Queue Functions -------------------------------------- */
+/** Ideally these should go in a seperate Header file (ie. queue.h) along with the self referencing structure
+ * 
+ * Note : Queue is a ADT which is also a derived DS from LinkedList
+ * 
+ * Queue Functions
+ * Create Node  : create_node
+ * Insert       : enqueue (append to the end of Queue)
+ * Delete       : dequeue (remove the first node of the Queue)
+ * Peek         : peek (views the first element in the queue)
+ * Display List : print_queue
+ * 
+ */
+
+// Creates a Node in Heap and returns a pointer
+Node * create_node(int data) {
+    Node *new_node = malloc(1 * sizeof(Node));
+    new_node->data = data;
+    new_node->next = NULL;
+
+    return new_node;
+}
+
+// appends a node to the end of the Queue
+void enqueue(Node **front, int data) {
+    if(*front == NULL) {
+        *front = create_node(data);
+    }else {
+        Node *current = *front;
+
+        while(current->next != NULL) {
+            current = current->next;
+        }
+
+        current->next = create_node(data);
+    }
+}
+
+// removes the first element in the queue
+void dequeue(Node **front) {        // Can be modified to return the removed Node | int according to the usage
+    if(*front == NULL) {
+        printf("Dequeue Failed : Empty Queue!!\n");
+        return;
+    }
+
+    Node *current = *front;
+
+    *front = current->next;
+
+    int deleted = current->data;
+
+    free(current);
+
+    printf("Dequeued : %d\n", deleted);
+
+}
+
+//Takes a peek at the first elemen in the queue
+void peek(Node *head) {
+    if(head == NULL) {
+        printf("Empty Queue!!\n");
+    }else {
+        printf("First Element of the Queue : %d\n", head->data);
+    }
+}
+
+// Prints all the elements in the Queue
+void print_queue(Node *head) {
+    if(head == NULL) {
+        printf("Empty Queue!!\n");
+        return;
+    }
+
+    printf("[");
+
+    while(head != NULL) {
+        printf(" %d", head->data);
+
+        if(head->next != NULL) printf(",");
+
+        head = head->next;
+    }
+
+    printf(" ]\n");
+}
+/* --------------------------------- End of Queue Functions ----------------------------------- */
+
+int main() {
+    Node *queue = NULL;         // Pointer to the First Node of the Queue
+
+    enqueue(&queue, 10);
+    enqueue(&queue, 30);
+    enqueue(&queue, 50);
+    enqueue(&queue, 60);
+
+    print_queue(queue);
+
+
+    dequeue(&queue);
+    dequeue(&queue);
+    peek(queue);
+
+    print_queue(queue);
+
+    return 0;
+}

Data Structures/Stack/stack.c

@@ -0,0 +1,113 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+//self referencing structure with one data element
+struct Node {
+    int data;
+    struct Node *next;
+};
+
+// Aliasing for easier referencing
+typedef struct Node Node; 
+
+/*-------------------------------------- Stack Functions -------------------------------------- */
+/** Ideally these should go in a seperate Header file (ie. stack.h) along with the self referencing structure
+ * 
+ * Stack Functions
+ * Create Node   : create_node
+ * Push          : push (adds an item to the top of the stack)
+ * Pop           : pop (removes the topmost item from the stack)
+ * Peek          : peek (take a look at the topmost item without popping)
+ * Display Stack : print_stack
+ * 
+ */
+
+Node * create_node(int data) {
+    Node *new_node = malloc(1 * sizeof(Node));
+
+    new_node->data = data;
+    new_node->next = NULL;
+
+    return new_node;
+}
+
+
+// adds a Node to the top of the stack
+void push(Node **top, int data) {
+    Node *new_node = create_node(data);
+
+    if(*top != NULL) {
+        new_node->next = *top;
+    }
+
+    *top = new_node;
+
+}
+
+// Pops the Top Node from the Stack
+int pop(Node **top) {
+    if(*top == NULL) {
+        printf("Popping Failed: Empty Stack !!\n");
+        return -1;
+    }
+
+    Node *popped = *top;
+
+    *top = popped->next;
+
+    int popped_int = popped->data;
+
+    free(popped);
+
+    printf("Successfully Popped : %d\n", popped_int);
+
+    return popped_int;
+}
+
+// Prints all the elements in the Stack
+void print_stack(Node *top) {
+    if(top == NULL) {
+        printf("Empty Stack!!\n");
+        return;
+    }
+
+    printf("[");
+
+    while(top != NULL) {
+        printf(" %d", top->data);
+
+        if(top->next != NULL) printf(",");
+
+        top = top->next;
+    }
+
+    printf(" ]\n");
+}
+
+//Prints the topmost item in the Stack 
+void peek(Node *top) {
+    if(top == NULL) {
+        printf("Empty Stack!!\n");
+    }else {
+        printf("First item of the Stack : %d\n", top->data);
+    }
+}
+
+/* --------------------------------- End of Stack Functions ----------------------------------- */
+
+int main() {
+    Node *stack = NULL;
+
+    push(&stack,10);
+    push(&stack,20);
+    push(&stack,50);
+
+    pop(&stack);
+    peek(stack);
+
+    push(&stack,40);
+    push(&stack,80);
+
+    print_stack(stack);
+
+}