LuckyTicketSubstring | Topcoder Archive

Problem Statement

A lucky ticket is an integer with exactly 2*n digits (written without leading zeroes), where the sum of the leftmost n digits is equal to the sum of the rightmost n digits.

You are given a String s, which contains only non-zero digits. Find the longest contiguous substring of s that is a lucky ticket and return its length. If there is no such lucky ticket, return 0 instead.

Definition

Class:: LuckyTicketSubstring
Method:: maxLength
Parameters:: String
Returns:: int
Method signature:: int maxLength(String s)
(be sure your method is public)

Constraints

s will contain between 1 and 50 characters, inclusive.
s will contain non-zero digits ('1'-'9') only.

Examples

```
"123231"
```
```
Returns: 6
```
The entire string, 123231, is a lucky ticket because the first 3 digits sum up to 1+2+3=6, and the last 3 digits sum up to 2+3+1=6.
```
"74233285"
```
```
Returns: 4
```
4233 is the longest lucky ticket here.

"986561517416921217551395112859219257312"

Returns: 36

```
"1"
```
```
Returns: 0
```
```
"112"
```
```
Returns: 2
```
A lucky ticket must contain an even number of digits.

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