Queue implementation in array

Author: AnushreeBagchi

implement_queue_array.py

@@ -0,0 +1,64 @@
+class Queue:
+    def __init__(self, initial_size= 10):
+        self.arr = [0 for _ in range(initial_size)]
+        self.front_index = -1
+        self.next_index = 0
+        self.queue_size = 0
+    def size(self):
+        return self.queue_size
+    def is_empty(self):
+        return self.queue_size == 0
+    def enqueue(self, value):
+        if self.queue_size == len(self.arr):
+            self.handle_capacity()
+        self.arr[self.next_index] = value
+        self.queue_size += 1
+        if self.front_index == -1:
+            self.front_index = 0
+        self.next_index = (self.next_index+1) % len(self.arr)
+    def dequeue(self):
+        if self.queue_size == 0:
+            self.next_index = 0
+            self.front_index = -1
+            return None
+        value = self.arr[self.front_index]
+        self.queue_size -= 1
+        self.front_index = (self.front_index+1)%len(self.arr)
+        return value
+    def handle_capacity(self):
+        old_arr = self.arr
+        self.arr = [0 for _ in range(2*len(self.arr))]
+        index = 0
+        for i in range(self.front_index, len(self.arr)):
+            self.arr[index] = old_arr[i]
+            index += 1
+        for i in range(0, self.front_index):
+            self.arr[index] = old_arr[i]
+            index += 1
+        self.front_index = 0
+        self.next_index = index
+
+q = Queue()
+q.enqueue(1)
+q.enqueue(2)
+q.enqueue(3)
+
+# Test size
+print ("Pass" if (q.size() == 3) else "Fail")
+
+# Test dequeue
+print ("Pass" if (q.dequeue() == 1) else "Fail")
+
+# Test enqueue
+q.enqueue(4)
+print ("Pass" if (q.dequeue() == 2) else "Fail")
+print ("Pass" if (q.dequeue() == 3) else "Fail")
+print ("Pass" if (q.dequeue() == 4) else "Fail")
+q.enqueue(5)
+print ("Pass" if (q.size() == 1) else "Fail")
+    
+        
+
+        
+
+