Created
January 11, 2014 02:14
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Starting in the top left corner of a 2×2 grid, and only being able to move to the right and down, there are exactly 6 routes to the bottom right corner. How many such routes are there through a 20×20 grid?
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| short = dict() | |
| def getPaths(x, y): | |
| if x == 0 and y == 0: | |
| return 0 | |
| if x == 0: | |
| return 1 | |
| if y == 0: | |
| return 1 | |
| if (x,y) in short: | |
| return short[x,y] | |
| # print x, y | |
| short[x,y] =getPaths(x, y - 1) + getPaths(x-1, y) | |
| return short[x,y] | |
| print getPaths(20, 20) |
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