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Barrett Ruth 2025-05-14 17:55:14 -04:00
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posts/algorithms/competitive-programming-log.html
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@ -32,6 +32,47 @@
<time datetime="2025-05-14">14/05/2025</time>
</span>
</h2>
<p>
First contest in a while. Implementation lacked heavily but solving
harder problems made easier problems easier.
</p>
<ul>
<li>
A: rust immediately showed with the brute force. Since \(n\cdot
m\leq 25\), at most \(\lceil\log_2(25)\rceil=5\) concatenations
need to be made. <b>Slow down and consider constrains</b>.
</li>
<li>
B: Similarly, mathematical insight and just
<i>playing with parameters</i>/quantifying the effects of
operations is important.
<b>Test your conjectures, they may be right/helpful</b> (ie. "I
must maintain the shortest length thread").
</li>
<li>
C: implementation weak. Simplify, step back, simplify,
continuously. I stopped considering altering the grid and used a
pair of coordinates but deriving the others inline,
<i>if you trust your mathematics</i>, is way simpler.
</li>
<li>
D: formalize your answer better. Understand prime factorization
more. Improve/memorize asymptotic bounds of factoring and prime
counting. Don't overcomplicate the problem&mdash;here, I
erroneously thought it was asking for minimum operations, not
possibility. In reality, all this problem asks is:
<blockquote>
"Are the total number of each factor greater than one divisible
by \(n\)?"
</blockquote>
</li>
<li>
E: dp rust. Simplify your thought process&mdash;look back into
SRTBOT (i.e. define the subproblem). If the subproblems depend
rightward, iterate right to left. That simple.
</li>
<li>F: coming back for you!</li>
</ul>
<p>
I must heed the advice of Colin Galen. I rush trivial problems
because they're boring, then forget an edge case. I get overwhelmed
@ -54,8 +95,8 @@
"this works"\(\rightarrow\) "let's simplify" \(\rightarrow\) "that
doesn't work" \(\rightarrow ...\) over and over again...
<i>even when the right solution comes across my mind</i>. In this
case, choosing an invariant was just overwhelming. <b>The simplest
correct solution is always the right one</b>.
case, choosing an invariant was just overwhelming.
<b>The simplest correct solution is always the right one</b>.
</p>
<h2>
<a href="https://usaco.guide/bronze/intro-complete" target="_blank"