Difference between revisions of "1997 PMWC Problems/Problem I15"
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segments (vertical, horizontal or inclined)? | segments (vertical, horizontal or inclined)? | ||
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== Solution == | == Solution == |
Revision as of 18:16, 8 October 2007
Problem
How many paths from A to B consist of exactly six line segments (vertical, horizontal or inclined)?
Solution
- Ignoring the diagonal segments, there are
paths.
- Traversing the diagonals, we quickly find that the path must run through exactly 2 diagonals. There are
pairs of diagonals through which this is possible; quick counting shows us that each pair of diagonals yields 2 paths. So there are 6 more cases here.
In total, we get paths.
See also
1997 PMWC (Problems) | ||
Preceded by Problem I14 |
Followed by Problem T1 | |
I: 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 T: 1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 |