growingPlant.R

# Caring for a plant can be hard work, but since you tend to it regularly, you
# have a plant that grows consistently. Each day, its height increases by a
# fixed amount represented by the integer upSpeed. But due to lack of sunlight,
# the plant decreases in height every night, by an amount represented by
# downSpeed.
#
# Since you grew the plant from a seed, it started at height 0 initially. Given
# an integer desiredHeight, your task is to find how many days it'll take for
# the plant to reach this height.
#
# Example
#
# For upSpeed = 100, downSpeed = 10, and desiredHeight = 910, the output should
# be growingPlant(upSpeed, downSpeed, desiredHeight) = 10.

# upSpeed = 100, downSpeed = 10 desiredHeight = 910
# upSpeed = 10 downSpeed = 9  desiredHeight = 4
# upSpeed = 7 downSpeed =  3 desiredHeight = 443

#todo: do without the while loop s
growingPlant <- function(upSpeed, downSpeed, desiredHeight) {
  prevHeight <- upSpeed
  days <- 1
  while (prevHeight < desiredHeight) {
    days <- days + 1
    prevHeight <- prevHeight - downSpeed + upSpeed 
  }
  return(days)
}