TopCoder problem "CrazySequence" used in TCHS SRM 36 (Division I Level Two)



Problem Statement

    Consider the following infinite sequence of numbers: 1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, ... (number k appears exactly k times in the sequence). You are given a String n representing an integer (without leading zeros). Return the n-th number in that sequence (index will be 1-based).
 

Definition

    
Class:CrazySequence
Method:nthNumber
Parameters:String
Returns:int
Method signature:int nthNumber(String n)
(be sure your method is public)
    
 

Constraints

-n will represent an integer between 1 and 1018, inclusive.
-n will have no leading zeros.
 

Examples

0)
    
"1"
Returns: 1
1)
    
"4"
Returns: 3
2)
    
"169"
Returns: 18
3)
    
"25342536783"
Returns: 225133

Problem url:

http://www.topcoder.com/stat?c=problem_statement&pm=8064

Problem stats url:

http://www.topcoder.com/tc?module=ProblemDetail&rd=10774&pm=8064

Writer:

mateuszek

Testers:

PabloGilberto , brett1479 , Olexiy , ivan_metelsky

Problem categories:

Math, Search