Filter | Topcoder Archive

Problem Statement

A 2-dimensional digital picture has been received from a satellite as a String[]. The characters in each String are only '0' or '1' (zero or one). Some of the '1's are noise that should be filtered out. The filtering rule is that a '1' should be removed if it is not part of a cross pattern consisting of 5 '1's in the following configuration:

     1
    111
     1

Write a class Filter that contains the method removable that takes a String[], picture, and returns the number of '1's that should be filtered out of picture.

Definition

Class:: Filter
Method:: removable
Parameters:: String[]
Returns:: int
Method signature:: int removable(String[] picture)
(be sure your method is public)

Notes

Cross patterns may overlap. (See example 2)

Constraints

picture contains between 1 and 50 elements, inclusive.
each String in picture contains between 1 and 50 characters, inclusive.
each String in picture has the same length.
each String in picture contains only the characters '0' and '1' (zero and one).

Examples

```
{"00110",
 "00110",
 "00110"}
```
```
Returns: 6
```
There are no cross patterns. All the '1's can be removed.
```
{"00110",
 "00111",
 "00110"}
```
```
Returns: 2
```
There is one cross pattern. 2 of the '1's can be removed.
```
{"00111",
 "01111",
 "00110"}
```
```
Returns: 1
```
There are two (overlapping) cross patterns. Only the 1 in the upper right corner is not in some cross.

This problem statement is the exclusive and proprietary property of Topcoder, Inc. Any unauthorized use or reproduction of this information without the prior written consent of Topcoder, Inc. is strictly prohibited. (c)2024, Topcoder, Inc. All rights reserved.