RollingLetters | Topcoder Archive

Problem Statement

A display mechanism is built from several spinning reels arranged in a line, from left to right. Each reel has a number of distinct letters on its perimeter, and only one of them is visible at a time. The visible letter changes every second. Each reel may have a different number of letters.

You are given a String[] reels, where reels[k] represents the letters on the k-th reel.

At time 0, each reel shows the letter at index 0 from the corresponding element of reels. At every second, the visible letter changes from the letter at index i to the letter at index i+1. Since reels are circular, the first letter shows up again after the last one.

Return the first second when the text displayed is equal to requiredText, or -1 if this will never happen.

Definition

Class:: RollingLetters
Method:: getTime
Parameters:: String[], String
Returns:: long
Method signature:: long getTime(String[] reels, String requiredText)
(be sure your method is public)

Notes

The return value will fit in a signed 64 bit integer.

Constraints

reels will contain between 1 and 50 elements, inclusive.
Each element of reels will contain between 2 and 26 uppercase letters ('A'-'Z'), inclusive.
Characters in each element of reels will be distinct.
requiredText will contain exactly N uppercase letters ('A'-'Z'), where N is the number of elements in reels.

Examples

```
{"XYZ", "DEF", "OPRS"}
```
```
"YES"
```
```
Returns: 7
```
The message displayed at each second is: 0: XDO 1: YEP 2: ZFR 3: XDS 4: YEO 5: ZFP 6: XDR 7: YES
```
{"ABC","ABC"}
```
```
"AB"
```
```
Returns: -1
```
The only possible messages are "AA", "BB", "CC".
```
{"ABC"}
```
```
"X"
```
```
Returns: -1
```
There is no 'X' on the reel.

{"CPKHFQEYXVMODNRTSGUBLJ", "TJLSURVHFQPAXGCEI", "JXNSGADPEWICKLFMVOQ", "UOFVKGQIJRECMWXADTPNL",
"OREWASJFLY", "HBEC", "ESDRVXCNQUFWKGTOLH", "CPLTAMBHYSQDVJIORNW", "CG"}

"CAIIEHLQC"

Returns: 4088392

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