reject = function(fx, a, b, k)
{
  while (1) {
    x = runif(1, a, b)
    y = runif(1, 0, k)
    if (y < fx(x)) return (x)
  }
}

fx = function(x)
{
  if (x <= 0) return (0)
  if (x >= 2) return (0)
  if (x < 1) return (x)
  return (2-x)
}

# n=5000
# z = rep(0, n)
# for (i in 1:n) z[i] = reject(fx, 0, 2, 1)
# hist(z, freq=FALSE, ylim=c(0,1.01))
# lines(c(0,1,2),c(0,1,0))