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Barrett Ruth 2025-04-07 12:05:28 -04:00
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<header class="post-header">
<h1 class="post-title">Practice Makes Perfect</h1>
<p class="post-meta">
<time datetime="2024-06-22">05/07/2024</time>
</p>
</header>
<article class="post-article">
<div>
Today I improved my implementation skills with
<a
href="https://codeforces.com/contest/1833/problem/G"
target="_blank"
>Codeforces Round 874 Div. 3 Problem G</a
>. Despite not solving the problem after a full 45 minutes, I came
across to the following realizations:
</div>
<ol>
<li>
Don't jump into coding. <i>Fully</i> flesh out your implementation
in your head before you begin. This is tempting to do, especially
in a "competitive" environment. I tend to do this to avoid
thinking about troublesome aspects of the problem that I
<i>know</i> I'll have to face later. Going into problems with a
plan makes things much easier when coding but much harder up
front. It is easy (for me) to get lost in the black-boxing four layers deep. Write it out, visualize it, and practice practice practice.
<blockquote>
Considering my solution would've led to me uncover my core
misinterpretation of the problem:
<b>the tree does not have to binary</b>. I developed a solution
for binary trees but the greedy logic cannot be extended to
trees.
</blockquote>
</li>
<li>
Complex problems are, well, hard. You <i>have</i> to practice to
internalize patterns so you can focus on the <i>crux</i> of the
problem.
<blockquote>
I spent 10 minutes debugging retrieving the leaves of a tree
before even beginning to code the actual algorithm.
<b>1800 is out of my skill range</b> (for now!).
</blockquote>
</li>
<li>
<b>Do not let a single thought/assertion/fact go unturned</b>. I
made a litany of erroneous assertions in my time thinking about
this problem, some of which include:
</li>
<ul>
<li>The tree has to be binary (it does not).</li>
<li>
I can gather the leaves in arbitrary order (once again, this
doesn't generalize to trees).
</li>
<li>
Ignore all cuts between identical nodes&mdash;it's fine! (I
didn't know why this was the case)
</li>
<li>
A set shouldn't be needed to track visited nodes in a
tree&mdash; slap it on anyway (this was superfluous and
should've immediately set off red flags that my parent-ignoring
policy in my BFS was wrong).
</li>
<li>
When processing a node in the "child-parent-child" pattern, just
pop off the next node from the queue (within binary/n-ary trees,
this is wrong&mdash;the leaves are gathered by <i>level</i>, so
the next node in the queue is not guaranteed to be the current's
sibling).
</li>
</ul>
<li>
Just because the solution passes the test cases does not mean it
is right. This specifically applies to problems near/outside your
skill range&mdash;create your own test cases.
</li>
</ol>
</article>
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