EllysViewPoints | Topcoder Archive

Problem Statement

Elly has a rectangular matrix with N rows and M columns. Each of the cells in the matrix can be either blocked (denoted '#') or free (denoted '.').

An empty cell is called a view point if we can see outside the matrix when looking directly in each of the four cardinal directions: north, south, east, and west. In other words, a cell C is a view point if and only if all cells in those four directions from cell C are free.

Below is an example matrix that contains six view points. One of these is marked by an asterisk ('*').

..#......
.....*...
.###..#..
.#.##..#.
...#..#..
.........

The girl has given you the ints N and M, as well as the String[] matrix. Return the number of view points in the given matrix.

Definition

Class:: EllysViewPoints
Method:: getCount
Parameters:: int, int, String[]
Returns:: int
Method signature:: int getCount(int N, int M, String[] matrix)
(be sure your method is public)

Constraints

N will be between 1 and 50, inclusive.
M will be between 1 and 50, inclusive.
matrix will contain exactly N elements.
Each element of matrix will contain exactly M characters.
Each character in matrix will be either '#' or '.'.

Examples

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

Returns: 6

The example from the problem statement.

```
1
```
```
1
```
```
{"."}
```
```
Returns: 1
```
It's pretty obvious which cell is the view point.

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

Returns: 0

With everything blocked, there are obviously no view points.

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

Returns: 18

Good luck!

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