CrazySequence | Topcoder Archive

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

```
"1"
```
```
Returns: 1
```
```
"4"
```
```
Returns: 3
```
```
"169"
```
```
Returns: 18
```
```
"25342536783"
```
```
Returns: 225133
```

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