# CONFIGURATION ---------------------------------------------------------------

RATIO   = 0.75          # Ratio of needle length to line spacing.
SAMPLES = 500000        # Number of times that the needle is dropped.
SEED    = 13            # Random seed for repeatability.

# -----------------------------------------------------------------------------

buffon <- function() {
  # Sample angle of needle with respect to lines.
  #
  theta = runif(1, 0, pi / 2)
  #
  # Sample the location of the needle's centre. Does the needle cross a line?
  #
  runif(1) <= RATIO * sin(theta)
}

set.seed(SEED)

cross = replicate(SAMPLES, buffon())
#
# Estimate pi.
#
cat(sprintf("ratio = %.3f / %6d samples -> estimate = %.6f\n", RATIO, SAMPLES, 2 * SAMPLES * RATIO / sum(cross)))