Solution 84: Pairs of Lattice Paths with Restrictions

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• Published on Mar 21, 2019
• Let's perform careful casework to formulate a recursive argument: How did the paths look like one step before?
Congratulations to Philip Yao, Gabriel N., Jeremy Weissmann, Kunal Gaurav, Evyatar Baranga, Rishav Gupta, Ruben van Erkelens, Nicola C, attyfarbuckle, and Mac KNÖDEL for successfully solving this week's math challenge question! Philip Yao was the first person to solve the question.
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• Sahil Baori 6 months ago

Can A and B go back and retrace their paths?

• LetsSolveMathProblems  6 months ago

In some sense, we are retracing the paths of A and B to establish the recurrence in the video. More precisely, to find the relationship between the number of pairs of A and B of length n and the number of pairs of A and B of length n-1, we are considering what should have happened at the final step of A and B AND how A and B should have looked like immediately before the final step in order to get the desired paths at the end.

• Sweety XS 6 months ago +2

Btw how much educated should we be to answer or understand this solution??

• Sweety XS 6 months ago +1

@Aaron He me too

• Aaron He 6 months ago +3

Probably a decent knowledge of recursive functions, which I don't have lol.

• Jeremy Weissmann 6 months ago +3

I may not have been the first to answer but it was nice to see you cover an approach similar to the one I used in this video!