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Diffstat (limited to 'new_21_game.py')
-rw-r--r-- | new_21_game.py | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/new_21_game.py b/new_21_game.py new file mode 100644 index 0000000..cc634d0 --- /dev/null +++ b/new_21_game.py @@ -0,0 +1,39 @@ +# 837. New 21 Game + +""" +alice plays the following game, loosely based on the card game "21". alice +starts with 0 points and draws numbers while she has less than 'k' points. +during each draw, she gains an integer number of points randomly from range +'[1, maxPts]', where 'maxPts' is an integer. each draw is independent and +the outcomes have equal posibilities. alice stops drawing numbers when she +gets 'k' or more points. return the probability that alice has 'n' or fewer +points. answers within 10^-5 of the actual answer are considered accepted +""" + + +class Solution(object): + def new21Game(self, n, k, maxPts): + """ + :type n: int + :type k: int + :type maxPts: int + :rtype: float + """ + if k == 0 or n >= k + maxPts: + return 1 + dp = [1.0] + [0.0] * n + sum = 1.0 + for i in range(1, n + 1): + dp[i] = sum / maxPts + if i < k: + sum += dp[i] + if i - maxPts >= 0: + sum -= dp[i - maxPts] + return sum(dp[k:]) + + +if __name__ == "__main__": + obj = Solution() + print(obj.new21Game(n=10, k=1, maxPts=10)) + print(obj.new21Game(n=6, k=1, maxPts=10)) + print(obj.new21Game(n=21, k=17, maxPts=10)) |