Enable Javascript in your browser and then refresh this page, for a much enhanced experience.
Recursive solution in Clear category for Pearls in the Box by panagiotakis.al
def recr(white, black, step, goal):
if step == goal:
return white / (white + black)
return (white / (white + black)) * recr(white - 1, black + 1, step + 1, goal) + (black / (white + black)) * recr(white + 1, black - 1, step + 1, goal)
def checkio(marbles, step):
return recr(marbles.count('w'), marbles.count('b'), 1, step)
#These "asserts" using only for self-checking and not necessary for auto-testing
if __name__ == '__main__':
assert checkio('bbw', 3) == 0.48, "1st example"
assert checkio('wwb', 3) == 0.52, "2nd example"
assert checkio('www', 3) == 0.56, "3rd example"
assert checkio('bbbb', 1) == 0, "4th example"
assert checkio('wwbb', 4) == 0.5, "5th example"
assert checkio('bwbwbwb', 5) == 0.48, "6th example"
July 11, 2014
