===python====
Problem 2:
http://www.lintcode.com/en/problem/search-for-a-range/#
http://pastebin.com/J3NtZ5kF

Problem 3:
http://www.lintcode.com/en/problem/recover-rotated-sorted-array/#
http://pastebin.com/Q0iLshxt

Problem 4:
http://www.lintcode.com/en/problem/implement-trie/
http://pastebin.com/hcba0RU0