13 lines
274 B
Python
13 lines
274 B
Python
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#!/usr/bin/env python3
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cache = [[{0 : 1} for b in range(10)] for a in range(10)]
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def f(i, a=0, b=0, fst=1):
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if i in cache[a][b]:
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return cache[a][b][i]
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r = sum((f(i-1, b, n, 0) for n in range(fst, 10-a-b)))
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cache[a][b][i] = r
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return r
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print(f(20))
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