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recursive solution in Clear category for Pearls in the Box by 1-more
def checkio(marbles, step):
return round(p(marbles.count('w'), marbles.count('b'), step), 2)
def p(w, b, s):
if s==1: return w/(w+b)
s-= 1
return (w*p(w-1, b+1, s) + b*p(w+1, b-1, s)) / (w+b)
#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"
March 4, 2018
