18 lines
346 B
Python
18 lines
346 B
Python
def C(n, k):
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if C.M[n][k]:
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return C.M[n][k]
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elif k == 0 or k == n:
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tmp = 1
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else:
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tmp = C(n - 1, k) + C(n - 1, k - 1)
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C.M[n][k] = tmp
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return tmp
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C.M = [[0] * (i + 1) for i in range(30)]
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C.M[0] = [1]
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C.M[1] = [1, 1]
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if __name__ == "__main__":
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print(C(*map(lambda x: int(x) - 1, input().split())))
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