queue

Author: hashfx

DSA-Python/DataStructures/queue.py

@@ -0,0 +1,61 @@
+''' 
+QUEUE
+    FIFO
+
+# All Enqueue and Dequeue operations are to/from the top of the stack, i.e., last modified elements
+Enqueue add an item to the end of the line
+Dequeue remove an item from the front of the line
+Enqueue from the one end and Dequeue from the another
+
+QUEUE USE CASE
+    Bank Tellers, Placing an order at restaurent, SuperMarket CheckOut
+# 
+    append() 
+        to enqueue an item to RightSide
+    appendleft() 
+        to enqueue an item to LeftSide
+    pop() 
+        to delete an item from RightSide
+    popleft() 
+        to dequeue an item off the queue from the LeftSide
+    index(ele, beg, end) 
+        returns first index of value mentioned in arguments from starting to end.
+    insert(i, a) 
+        inserts value mentioned in arguments(a) at index(i) specified in arguments.
+    remove() 
+        removes first occurrence of value mentioned in arguments. 
+    count() 
+        counts number of occurrences of value mentioned in arguments. 
+'''
+
+
+''' CLASS QUEUE() '''
+
+''' CLASS QUEUE() END '''
+
+
+from collections import deque
+queue = deque()
+queue.append(5)
+queue.append(4)
+queue.append(3)
+queue.append(2)
+queue.append('A')
+
+print(f"Queue is {queue}", end="\n\n")
+
+queue.popleft()
+print(f"Popping FIRST item {queue}", end="\n\n")
+
+# insert(), index(), remove(), count()
+
+print (f"Index of 2 between index 0&3 is {queue.index(3,1,4)}", end="\n\n") # index(ele, begi, endi) : return First repetitive_index of element
+  
+queue.insert(3,1) # insert(index,val)
+print (f"Queue after inserting 1 at index3 {queue}", end="\n\n")
+    
+print (f"1 has been repeated {queue.count(1)} times", end="\n\n")
+  
+queue.remove(3)
+print (f"Deleting first occurrence of 3 is{queue}", end="\n\n")
+