diff --git a/posts/algorithms/cp-log.html b/posts/algorithms/cp-log.html index fe30e69..e905a1f 100644 --- a/posts/algorithms/cp-log.html +++ b/posts/algorithms/cp-log.html @@ -191,97 +191,108 @@ Everyone recommends CSES so I started with it, doing the first 8 problems.
-Trivial, but I forgot to print 1 at the end.
-- Return the exactly correct answer. -
-N/A
-Use invariants.
-
- Run through one iteration of the algorithm. Here, I erroneously
- added x - last to a quantity,
- after manipulating x.
-
- I'd seen this problem before yet struggled.
- Fully understand the problem constraints. In this case, While
- I understood the definition of a permissible permutation, I didn't
- fully internalize that you could place number wherever you
- want. Instead, I was locked in on placing some x at
- i, i + 2, i + 4, .... Further, the fact that I didn't
- immediately recognize this solution means I need to improve at
- upsolving and reviewing problems.
-
- Absolutely disastrous. I continually just f*dged with the offsets I - was adding to my strategy until I happened to get the answer right. - Don't guess. Also, - don't be lazy—if an algorithm works, focus, write it out, - and enjoy being correct. -
-- Required 2 hints from Sam Altman. git gud at combinatorics. - Use the paradigm "count good, remove bad." Lock in less on counting - specifics—instead, consider what objects - mean in aggregate. In this case, a \(2\times3\) grid - represents an "area" of attack, contributing 2 bad knight pairs. - This is much easier to digest then attempting to remove overcounting - per-knight. Fundamentally, the problem involves placing 2 knights, - so breaking it down 2 knights at a time is the most intuitive take. -
-- Don't lock in on one approach. Here, this is dp. The fact - that I knew the idea of partitioning the first \(n\) numbers into - two groups of size \(\frac{n(n+1)}{4}\) but failed to recognize the - greedy approach means I didn't grasp the fundamental arithmetic of - the problem, nor the greedy idea: every number must go into a set. - If you add the largest number possible to set 1 to not exceed the - target, this number can always be formed in the other set by - choosing \(1\) and \(x-1\). git gud at greedy. -
+x - last to a quantity,
+ after manipulating x.
+ x at i, i + 2, i + 4, .... Further, the
+ fact that I didn't immediately recognize this solution means I
+ need to improve at upsolving and reviewing problems.
+