284. Peeking Iterator

Loading Question ...

Given an Iterator class interface with methods: next() and hasNext(), design and implement a PeekingIterator that support the peek() operation -- it essentially peek() at the element that will be returned by the next call to next().


Here is an example. Assume that the iterator is initialized to the beginning of the list: [1, 2, 3].

Call next() gets you 1, the first element in the list.

Now you call peek() and it returns 2, the next element. Calling next() after that still return 2.

You call next() the final time and it returns 3, the last element. Calling hasNext() after that should return false.

Follow up: How would you extend your design to be generic and work with all types, not just integer?

Credits:
Special thanks to @porker2008 for adding this problem and creating all test cases.


Seen this question in a real interview before?  
Yes
No
When did you encounter this question?  
last week
last month
last 3 month
last 6 month
more than 6 months
other
Which company?  
Adobe
Aetion
Airbnb
Alibaba
Amazon
Apple
Baidu
Bloomberg
Cloudera
Coursera
Cryptic Studios
Dropbox
eBay
Epic Systems
Expedia
Facebook
Fallible
Games
Gilt Groupe
GoDaddy
Goo
Google
Hedvig
Houzz
Hulu
Indeed
Intuit
IXL
LinkedIn
LiveRamp
Lyft
MAQ Software
Mathworks
Microsoft
NetEase
Netsuite
Palantir
Palantir Technologies
Pinterest
Pocket Gems
Poynt
Pure
Pure Storage
Rackspace
Riot
Riot Games
Samsung
Snapchat
Square
Storage
Tencent
TinyCo
Twitter
Two Sigma
Uber
Valve
WAP
Works Applications
Yahoo
Yahoo!
Yelp
Zappos
Zenefits