From 720658bf477b5b3c7f73cbb3bc9d0d6d25cb44ff Mon Sep 17 00:00:00 2001
From: Barrett Ruth <br.barrettruth@gmail.com>
Date: Sat, 22 Mar 2025 15:50:49 -0400
Subject: [PATCH] feat(cp): codeforces 900 div 3

---
 posts/algorithms/cp-log.html | 59 +++++++++++++++++++++++++++++++++++-
 1 file changed, 58 insertions(+), 1 deletion(-)

diff --git a/posts/algorithms/cp-log.html b/posts/algorithms/cp-log.html
index 80c94f5..cdab38a 100644
--- a/posts/algorithms/cp-log.html
+++ b/posts/algorithms/cp-log.html
@@ -35,6 +35,60 @@
           <h1 class="post-title">Competitive Programming Log</h1>
         </header>
         <article class="post-article">
+          <h2>
+            <a href="https://codeforces.com/contest/1878/" target="_blank"
+              >900 (div. 3)</a
+            >&mdash;22/3/2025
+          </h2>
+          <div>
+            <p>
+              Solved in a coffee shop. Used AI for smaller things (otherwise I'd
+              have no idea).
+            </p>
+            <ul>
+              <li>
+                A: Solved a much harder problem related to majority element
+                paths on tree&mdash;realized the solution after a minute.
+              </li>
+              <li>
+                B: was confused for about 7 minutes but realized some properties
+                of divisibility and odd numbers.
+                <b
+                  >Math is still a weakness. Take simpler approaches to complex
+                  constraints, such as considering parity.</b
+                >
+              </li>
+              <li>
+                Went off of gut instinct that it is always possible to form the
+                given \(x\) if encompassed in the range of numbers.
+                <b
+                  >Failed to prove this mathematical validity but had fair
+                  intuition</b
+                >
+                (i.e. just "take off one" if too big/small). This is acceptable,
+                though not perfect.
+              </li>
+              <li>
+                D: cooked. Solved E first and had mentally given up by this
+                point.
+                <b
+                  >If you've given up, just stop trying and take a break/do
+                  something else. You're wasting your time.</b
+                >
+              </li>
+              <li>
+                E: incredibly easy with segtree. Realized the lower bound/walk
+                solution after 2-3 minutes. Binary search indexing can be
+                improved (i.e. which pointer to return?) as well as realizing
+                one binary search is necessary across both arrays. Good
+                mathematical deduction to realize relationship between input
+                arrays. Revisit sparse table + simpler solution&mdash;<i
+                  >don't be content with an advanced solution when a
+                  simpler/elegant idea also suffices</i
+                >.
+              </li>
+            </ul>
+          </div>
           <h2>
             <a href="https://codeforces.com/contest/1857/" target="_blank"
               >891 (div. 3)</a
@@ -111,7 +165,10 @@
                 but thanks Deepseek).
                 <b>Overflow, again. rly dude?</b>
               </li>
-              <li>F: doing this later, got the core insight of the minimal weight edge path. Once again, for surveying path </li>
+              <li>
+                F: doing this later, got the core insight of the minimal weight
+                edge path. Once again, for surveying path
+              </li>
             </ol>
           </div>
           <h2>cses (range queries, sorting and searching)&mdash;1/3/2025</h2>