CardRemover | Topcoder Archive

Problem Statement

There are some cards placed in a line. Each card is characterized by the three distinct letters written on it.

The conformity-level of two cards is the number of distinct letters that are common to both cards. For example, the conformity-level of "ABC" and "ACD" is 2 because the letters 'A' and 'C' are common to both cards, and the conformity-level of "ABC" and "DFE" is 0 because the two cards share no common letters.

You can remove a card if the conformity-level of its left neighbor and its right neighbor is greater than or equal to 2. Once a card is removed its left and right neighbors become neighbors themselves. The leftmost and rightmost cards are never removed.

Given a String[] cards, determine the maximum quantity of cards that you can remove.

Definition

Class:: CardRemover
Method:: calculate
Parameters:: String[]
Returns:: int
Method signature:: int calculate(String[] cards)
(be sure your method is public)

Constraints

cards will have between 2 and 50 elements, inclusive.
Each element of cards will contain exactly 3 characters.
Each element of cards will contain three distinct uppercase letters ('A'-'Z').

Examples

```
{"ABC",
 "CDE",
 "ABC",
 "CDE",
 "ABC"}
```
```
Returns: 3
```
You should not remove the third card before the second or the fourth.

{"ABC",
 "CDE",
 "EFG",
 "GHI",
 "IJK"}

Returns: 0

You can't remove anything.

{"ADR",
 "FDB",
 "ABC",
 "CDE",
 "ABD"}

Returns: 3

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