<?xml version="1.0" encoding="utf-8" standalone="yes"?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom"><channel><title>Heroctf on Anthrace | CTF Writeups</title><link>https://anthr4ce.github.io/tags/heroctf/</link><description>Recent content in Heroctf on Anthrace | CTF Writeups</description><generator>Hugo</generator><language>en-us</language><lastBuildDate>Mon, 28 Oct 2024 00:00:00 +0000</lastBuildDate><atom:link href="https://anthr4ce.github.io/tags/heroctf/index.xml" rel="self" type="application/rss+xml"/><item><title>HeroCTF - DataScience</title><link>https://anthr4ce.github.io/ctf-writeups/heroctf/</link><pubDate>Mon, 28 Oct 2024 00:00:00 +0000</pubDate><guid>https://anthr4ce.github.io/ctf-writeups/heroctf/</guid><description>&lt;hr&gt;&#10;&lt;p&gt;In this challenge, we had to sort data and calculate specific values.&#10;After several attempts, I arrived at the following code:&lt;/p&gt;&#10;&lt;div class="highlight"&gt;&lt;pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"&gt;&lt;code class="language-python" data-lang="python"&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&lt;span style="color:#f92672"&gt;import&lt;/span&gt; pandas &lt;span style="color:#66d9ef"&gt;as&lt;/span&gt; pd &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&lt;span style="color:#f92672"&gt;import&lt;/span&gt; math &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;df &lt;span style="color:#f92672"&gt;=&lt;/span&gt; pd&lt;span style="color:#f92672"&gt;.&lt;/span&gt;read_csv(&lt;span style="color:#e6db74"&gt;&amp;#34;orders.csv&amp;#34;&lt;/span&gt;, parse_dates&lt;span style="color:#f92672"&gt;=&lt;/span&gt;[&lt;span style="color:#e6db74"&gt;&amp;#34;date&amp;#34;&lt;/span&gt;]) &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;df &lt;span style="color:#f92672"&gt;=&lt;/span&gt; df[df[&lt;span style="color:#e6db74"&gt;&amp;#34;date&amp;#34;&lt;/span&gt;] &lt;span style="color:#f92672"&gt;&amp;lt;&lt;/span&gt; &lt;span style="color:#e6db74"&gt;&amp;#34;2023-01-01&amp;#34;&lt;/span&gt;] &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;initial_balance &lt;span style="color:#f92672"&gt;=&lt;/span&gt; &lt;span style="color:#ae81ff"&gt;10000&lt;/span&gt; &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;user_balances &lt;span style="color:#f92672"&gt;=&lt;/span&gt; {} &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;unique_users &lt;span style="color:#f92672"&gt;=&lt;/span&gt; pd&lt;span style="color:#f92672"&gt;.&lt;/span&gt;concat([df[&lt;span style="color:#e6db74"&gt;&amp;#34;buyer_id&amp;#34;&lt;/span&gt;], df[&lt;span style="color:#e6db74"&gt;&amp;#34;seller_id&amp;#34;&lt;/span&gt;]])&lt;span style="color:#f92672"&gt;.&lt;/span&gt;unique() &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;user_balances &lt;span style="color:#f92672"&gt;=&lt;/span&gt; {}&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&lt;span style="color:#66d9ef"&gt;for&lt;/span&gt; user_id &lt;span style="color:#f92672"&gt;in&lt;/span&gt; unique_users:&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt; user_balances[user_id] &lt;span style="color:#f92672"&gt;=&lt;/span&gt; initial_balance&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;total_discount_spared &lt;span style="color:#f92672"&gt;=&lt;/span&gt; &lt;span style="color:#ae81ff"&gt;0&lt;/span&gt; &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&lt;span style="color:#66d9ef"&gt;for&lt;/span&gt; _, row &lt;span style="color:#f92672"&gt;in&lt;/span&gt; df&lt;span style="color:#f92672"&gt;.&lt;/span&gt;iterrows(): &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt; buyer_id &lt;span style="color:#f92672"&gt;=&lt;/span&gt; row[&lt;span style="color:#e6db74"&gt;&amp;#34;buyer_id&amp;#34;&lt;/span&gt;] &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt; seller_id &lt;span style="color:#f92672"&gt;=&lt;/span&gt; row[&lt;span style="color:#e6db74"&gt;&amp;#34;seller_id&amp;#34;&lt;/span&gt;] &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt; price &lt;span style="color:#f92672"&gt;=&lt;/span&gt; row[&lt;span style="color:#e6db74"&gt;&amp;#34;price&amp;#34;&lt;/span&gt;] &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt; discount &lt;span style="color:#f92672"&gt;=&lt;/span&gt; row[&lt;span style="color:#e6db74"&gt;&amp;#34;discount&amp;#34;&lt;/span&gt;] &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt; discounted_price &lt;span style="color:#f92672"&gt;=&lt;/span&gt; price &lt;span style="color:#f92672"&gt;*&lt;/span&gt; (&lt;span style="color:#ae81ff"&gt;1&lt;/span&gt; &lt;span style="color:#f92672"&gt;-&lt;/span&gt; discount &lt;span style="color:#f92672"&gt;/&lt;/span&gt; &lt;span style="color:#ae81ff"&gt;100&lt;/span&gt;) &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt; amount_spared &lt;span style="color:#f92672"&gt;=&lt;/span&gt; price &lt;span style="color:#f92672"&gt;-&lt;/span&gt; discounted_price &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt; total_discount_spared &lt;span style="color:#f92672"&gt;+=&lt;/span&gt; amount_spared &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt; user_balances[buyer_id] &lt;span style="color:#f92672"&gt;-=&lt;/span&gt; discounted_price &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt; user_balances[seller_id] &lt;span style="color:#f92672"&gt;+=&lt;/span&gt; discounted_price &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&lt;span style="color:#75715e"&gt;# resp 1 &lt;/span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;richest_user &lt;span style="color:#f92672"&gt;=&lt;/span&gt; max(user_balances, key&lt;span style="color:#f92672"&gt;=&lt;/span&gt;user_balances&lt;span style="color:#f92672"&gt;.&lt;/span&gt;get) &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&lt;span style="color:#75715e"&gt;# resp 2 &lt;/span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;total_discount_spared &lt;span style="color:#f92672"&gt;=&lt;/span&gt; math&lt;span style="color:#f92672"&gt;.&lt;/span&gt;floor(total_discount_spared) &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&lt;span style="color:#75715e"&gt;# resp 3 &lt;/span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;negative_balance_count &lt;span style="color:#f92672"&gt;=&lt;/span&gt; &lt;span style="color:#ae81ff"&gt;0&lt;/span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&lt;span style="color:#66d9ef"&gt;for&lt;/span&gt; balance &lt;span style="color:#f92672"&gt;in&lt;/span&gt; user_balances&lt;span style="color:#f92672"&gt;.&lt;/span&gt;values():&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt; &lt;span style="color:#66d9ef"&gt;if&lt;/span&gt; balance &lt;span style="color:#f92672"&gt;&amp;lt;&lt;/span&gt; &lt;span style="color:#ae81ff"&gt;0&lt;/span&gt;:&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt; negative_balance_count &lt;span style="color:#f92672"&gt;+=&lt;/span&gt; &lt;span style="color:#ae81ff"&gt;1&lt;/span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;&lt;span style="color:#75715e"&gt;#print the flag &lt;/span&gt;&#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;flag &lt;span style="color:#f92672"&gt;=&lt;/span&gt; &lt;span style="color:#e6db74"&gt;f&lt;/span&gt;&lt;span style="color:#e6db74"&gt;&amp;#34;Hero&lt;/span&gt;&lt;span style="color:#ae81ff"&gt;{{&lt;/span&gt;&lt;span style="color:#e6db74"&gt;{&lt;/span&gt;richest_user&lt;span style="color:#e6db74"&gt;}&lt;/span&gt;&lt;span style="color:#e6db74"&gt;_&lt;/span&gt;&lt;span style="color:#e6db74"&gt;{&lt;/span&gt;total_discount_spared&lt;span style="color:#e6db74"&gt;}&lt;/span&gt;&lt;span style="color:#e6db74"&gt;_&lt;/span&gt;&lt;span style="color:#e6db74"&gt;{&lt;/span&gt;negative_balance_count&lt;span style="color:#e6db74"&gt;}&lt;/span&gt;&lt;span style="color:#ae81ff"&gt;}}&lt;/span&gt;&lt;span style="color:#e6db74"&gt;&amp;#34;&lt;/span&gt; &#10;&lt;/span&gt;&lt;/span&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;print(flag)&#10;&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;&lt;div class="highlight"&gt;&lt;pre tabindex="0" style="color:#f8f8f2;background-color:#272822;-moz-tab-size:4;-o-tab-size:4;tab-size:4;-webkit-text-size-adjust:none;"&gt;&lt;code class="language-t" data-lang="t"&gt;&lt;span style="display:flex;"&gt;&lt;span&gt;Hero{&lt;span style="color:#ae81ff"&gt;732669_188098001_3468&lt;/span&gt;}&#10;&lt;/span&gt;&lt;/span&gt;&lt;/code&gt;&lt;/pre&gt;&lt;/div&gt;</description></item></channel></rss>