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LintCode 492 Implement Queue By Linked List - Easy

492. Implement Queue by Linked List

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492. Implement Queue By Linked List — Easy

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Problem

  1. Implement Queue by Linked List

Implement a Queue by linked list. Support the following basic methods:

enqueue(item). Put a new item in the queue. dequeue(). Move the first item out of the queue, return it. Example Example 1:

Input: enqueue(1) enqueue(2) enqueue(3) dequeue() // return 1 enqueue(4) dequeue() // return 2 Example 2:

Input: enqueue(10) dequeue()// return 10

Solution

class MyQueue(object):
 
    def __init__(self):
        # do some intialize if necessary
        self.first, self.last = None, None
 
    # @param {int} item an integer
    # @return nothing
    def enqueue(self, item):
        # Write yout code here
        if self.first is None:
            self.first = Node(item)
            self.last = self.first
        else:
            self.last.next = Node(item)
            self.last = self.last.next
 
    # @return an integer
    def dequeue(self):
        # Write your code here
        if self.first is not None:
            item = self.first.val
            self.first = self.first.next
            return item
 
        return -1000
 
class Node():
 
    def __init__(self, _val):
        self.next = None
        self.val = _val

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