Cross | Topcoder Archive

Problem Statement

There is a rectangular board that is divided into n rows by m columns of cells. Each cell is either black or white. You are given the description of the board in the String[] board. Each character in board represents one cell. More precisely, the character board[i][j] represents the cell at coordinates (row i, column j). The character '#' represents a black cell, the character '.' is a white cell.

You want to find a cross on this board. A cross is a configuration of 5 black cells placed like this:

 #
###
 #

Formally, there is a cross centered at (x, y) if the following five cells are all black: (x, y), (x+1, y), (x-1, y), (x, y-1), and (x, y+1). Note that other cells adjacent to the cross may also be black, it is still a valid cross.

Return "Exists" if there is at least one cross on the given board. Otherwise, return "Does not exist". Note that the return value is case-sensitive.

Definition

Class:: Cross
Method:: exist
Parameters:: String[]
Returns:: String
Method signature:: String exist(String[] board)
(be sure your method is public)

Constraints

n, m will be between 3 and 50, inclusive.
board will contain exactly n elements.
Each element in board will contain exactly m characters.
Each character in board will be either '#' or '.'.

Examples

```
{".##",
 "###",
 "##."}
```
```
Returns: "Exist"
```
There is a cross centered at (1,1).

{".##",
 "###",
 "#.."}

Returns: "Does not exist"

This time there is no cross.

{"######",
 "######",
 "######",
 "######",
 "######",
 "######",
 "######"}

Returns: "Exist"

{".#.#",
 "#.#.",
 ".#.#",
 "#.#."}

Returns: "Does not exist"

{".#.#",
 "###.",
 ".###",
 "#.#."}

Returns: "Exist"

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