21 lines
413 B
Python
21 lines
413 B
Python
N = int(input())
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Mem = [[0] * 10 for i in range(100)]
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def I(l, k):
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if 0 <= k <= 9:
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if l == 1:
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return 1
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elif Mem[l-1][k] != 0:
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return Mem[l-1][k]
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else:
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temp = (I(l - 1, k - 1) + I(l - 1, k + 1)) % 1000000000
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Mem[l-1][k] = temp
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return temp
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else:
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return 0
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print(sum(I(N, i) for i in range(1, 10)) % 1000000000)
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