Added Double ended queue to C(#126)

* Added double ended queue using array

* replace space( ) to dash(-)

* remove space complexity 

removed space complexity because i did know how to check space complexity

* done the requested changes

* update queue index readme

add double-ended-queue-using-array.c under c-or-cpp

Co-authored-by: Arsenic <54987647+Arsenic-ATG@users.noreply.github.com>

queues/README.md

@@ -4,3 +4,4 @@
 
 1. [Queue using linked list](c-or-cpp/queue-linked-list.cpp)
 2. [Circular Queue using linked list](c-or-cpp/circular-queue-linked-list.cpp)
+3. [Double Ended Queue (using arrays)](c-or-cpp/double-ended-queue-using-array.c)

queues/c-or-cpp/double-ended-queue-using-array.c

@@ -0,0 +1,203 @@
+/* this is a double ended queue implementation using array
+means you can insert or delete data from both front and rear */
+//included necessary header file
+#include<stdio.h>
+#include<stdlib.h>
+// creating non-primitive named deque using structure concept
+struct deque
+{
+    //declaring necessary variable
+    int front;
+    int rear;
+    int capacity;
+    int *arr;
+
+};
+// clear function for different platforms ( currently only windows and unix based os are supported )
+void clear_screen()
+{
+    #ifdef _WIN32
+        system("cls");
+    #elif __unix__
+        system("clear");
+    #else
+        printf("clear screen not supported\n");
+    #endif
+}
+//create deque function mainly give memory to the non-primitive variable deque
+struct deque* create_dequeue(int cap)
+{
+ struct deque *array;
+ // dynamically giving memory
+ array=(struct deque*)malloc(sizeof(struct deque));
+ // declaring default value of cap front rear
+ array->capacity=cap;
+ array->front=-1;
+ array->rear=-1;
+// dynamically giving memory
+ array->arr=(int*)malloc(sizeof(int)*cap);
+ return(array);
+}
+// insertion front just insert data from front of queue
+void insertion_front(struct deque *array,int data)
+{
+    // checking that whether the queue is not full
+if(array->rear+1==array->front||array->rear==array->capacity-1&&array->front==0)
+    printf("queue is full");
+//checking is the front equal to -1 means queue is empty or not
+    else if(array->front==-1)
+    {
+        array->front=0;
+        array->rear=0;
+        array->arr[array->front]=data;
+    }
+    // checking whether the queue has 1 data or not
+    else if(array->front==0)
+{
+ array->front=array->capacity-1;
+array->arr[array->front]=data;
+}
+// normal condition
+else
+{
+    array->front--;
+    array->arr[array->front]=data;
+}
+}
+// insertion rear basically insert data from end of a queue
+void insertion_rear(struct deque *array,int data)
+{
+    //checking is the front equal to -1 means queue is empty or not
+    if(array->rear==array->capacity-1&&array->front==0||array->rear+1==array->front)
+    printf("queue is full");
+    //checking is the rear equal to -1 means queue is empty or not
+else if(array->rear==-1)
+	{
+	    array->rear++;
+	    array->arr[array->rear]=data;
+	    array->front=array->rear;
+	}
+	// checking whether queue is full from rear but not from front
+	else if(array->rear==array->capacity-1&&array->front!=0)
+	{
+	    array->rear=0;
+	    array->arr[array->rear]=data;
+	}
+	// normal condition
+	else
+	{
+	    array->rear++;
+	    array->arr[array->rear]=data;
+	}
+
+}
+// deletion front basically delete data from front of queue
+void deletion_front(struct deque *array)
+{
+    // queue empty condition
+    if(array->front==-1)
+	printf("queue is empty");
+    else
+    {
+        // printing the value which is going to be deleted
+    printf("deleted value is %d",array->arr[array->front]);
+    // checking whether the queue has only one data
+	if(array->front==array->rear)
+	{
+	    array->front=-1;
+	    array->rear=-1;
+	}
+	// checking whether front is equal to capacity-1
+	else if(array->front==array->capacity-1)
+	    array->front=0;
+	// normal condition
+	else
+	    array->front++;
+
+
+ }
+}
+// deletion rear basically delete data from end of queue
+void deletion_rear(struct deque *array)
+{
+    //empty condition
+    if(array->rear==-1)
+      printf("queue is empty");
+      else
+      { printf("deleted value is %d",array->arr[array->rear]);
+    // checking whether the queue has only one data
+          if(array->rear==array->front)
+          {
+        array->front=-1;
+	    array->rear=-1;
+          }
+          // checking whether rear is 0 but there not only one data left that means that data are at end of queue
+          else if(array->rear==0)
+            array->rear=array->capacity-1;
+            //normal condition
+          else
+            array->rear--;
+      }
+}
+// menu basically provide the no. of task can be performed so you can choose one of them
+int menu(void)
+{
+    int choice;
+    printf("\n1: Insertion at Front");
+    printf("\n2: Insertion at Rear");
+    printf("\n3: Deletion at Front");
+    printf("\n4: Deletion at Rear");
+    printf("\n5: exit");
+    printf("\n\n enter your choice");
+    scanf("%d",&choice);
+    return(choice);
+}
+// driver code
+int main()
+{
+    struct deque *array;
+    int cap,data;
+    printf("enter the capacity");
+    scanf("%d",&cap);
+    array=create_dequeue(cap);
+    while(1)
+    { clear_screen();
+        switch(menu())
+        {
+        case 1:
+            printf("enter value");
+            scanf("%d",&data);
+            insertion_front(array,data);
+            break;
+        case 2:
+            printf("enter value ");
+            scanf("%d",&data);
+            insertion_rear(array,data);
+            break;
+        case 3:
+            deletion_front(array);
+            break;
+        case 4:
+            deletion_rear(array);
+            break;
+        case 5:
+            exit(0);
+        }
+
+    }
+return 0;
+
+}
+/*
+Input: Insert 3 at front
+       Insert 2 at rear
+       Insert 5 at rear
+       Delete from rear
+       delete from front
+Output:
+5 had been deleted
+3 had been deleted
+Time complexity:O(n)
+
+*/
+