20 lines
410 B
Python
20 lines
410 B
Python
#Lattice paths
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#Problem 15
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#
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#Starting in the top left corner of a 2x2 grid, and only being able to move to the right and down, there are exactly 6 routes to the bottom right corner.
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#__ _ _
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#
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#How many such routes are there through a 20x20 grid?
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#
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#Solution:
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a = 1
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b = 1
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for i in range(21,41):
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a *= i
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b *= i-20
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print( a//b )
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