ABC034C
https://gyazo.com/02309bcb5a4e2e7fc98cd80f757482e8
Thoughts.
Isn't it simply DP?
No. A simple DP would be 10^10 for the largest case, so it's impossible.
Is it a problem that can be mathematically transformed to arrive at a solution of smaller order?
This is, in essence, asking for the number of ways to choose the H times to move vertically out of the W+H times, so we can find $ C(W+H, H).
Official Explanation
I've read about finding the inverse of the factorial to get this, but it's known to me.
Did I put this together on one of the pages?
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