Game of life (1)

The English mathematician John Conway invented in 1970 the following
game: Imagine a matrix with n rows and m columns. We consider neighbor
positions to a given position the (at most, eight) adjacent positions,
either horizontally, vertically or diagonally. Every moment, each
position is either empty or it contains a bacterium. The rules are:

- An empty position at time t will contain a bacterium at time t + 1 if
  and only if at time t it had exactly three neighbor bacteria.

- An occupied position at time t will contain a bacterium at time t + 1
  if and only if at time t it had two or three neighbor bacteria.

Write a program that, for every given matrix, prints it at the next
moment of time.

Input

Input consists of several cases. Every case begins with n and m (both
strictly positive), followed by n lines, each one with m characters: ‘B’
if the position has a bacterium, and ‘.’ if the position is empty. A
special case with n = m = 0 marks the end of the input.

Output

For each case, print the matrix corresponding to the next moment of time
using the same format of the input (do not print n and m). Separate
matrices with an empty line.

Problem information

Author: Unknown
Translator: Carlos Molina

Generation: 2026-01-25T10:28:06.981Z

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