Counting Numbers | CSES Problem | Digit DP Explained | No Adjacent Equal Digits

🔢 𝐂𝐒𝐄𝐒 – 𝐂𝐨𝐮𝐧𝐭𝐢𝐧𝐠 𝐍𝐮𝐦𝐛𝐞𝐫𝐬 | 𝐃𝐢𝐠𝐢𝐭 𝐃𝐏 𝐒𝐨𝐥𝐮𝐭𝐢𝐨𝐧 𝐄𝐱𝐩𝐥𝐚𝐢𝐧𝐞𝐝 (𝐍𝐨 𝐀𝐝𝐣𝐚𝐜𝐞𝐧𝐭 𝐒𝐚𝐦𝐞 𝐃𝐢𝐠𝐢𝐭𝐬)⁣ ⁣ In this video, we solve the Counting Numbers problem from the CSES Problem Set, using one of the most fundamental techniques in competitive programming: Digit DP (Number DP).⁣ ⁣ We explore the idea of counting all numbers in a range [a,b] such that no two adjacent digits are equal — a perfect beginner-friendly problem for building intuition in Digit DP.⁣ ⁣ This video covers everything from concept → state design → transitions → implementation in C++.⁣ ⁣ 💡 𝐖𝐡𝐚𝐭 𝐘𝐨𝐮’𝐥𝐥 𝐋𝐞𝐚𝐫𝐧⁣ ⁣ - What is Digit DP?⁣ - How to design DP states:⁣ - position⁣ - previous digit⁣ - tight constraint⁣ - leading zero logic⁣ - Handling range queries using countUpTo(b) – countUpTo(a-1)⁣ - Avoiding adjacent equal digits⁣ - Clean, contest-ready C++ implementation⁣ - Understanding a classic CSES DP problem step-by-step⁣ ⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ ⁣⁣⁣This is part of my 𝐃𝐢𝐠𝐢𝐭 𝐃𝐏 𝐒𝐞𝐫𝐢𝐞𝐬, where I cover smart and creative problems that teach you how to build solutions from logic — a key skill in competitive programming 🚀⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ ⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ 💡 𝐓𝐡𝐢𝐬 𝐯𝐢𝐝𝐞𝐨 𝐰𝐢𝐥𝐥 𝐡𝐞𝐥𝐩 𝐲𝐨𝐮 𝐮𝐧𝐝𝐞𝐫𝐬𝐭𝐚𝐧𝐝 𝐡𝐨𝐰 𝐭𝐨 𝐭𝐡𝐢𝐧𝐤 𝐜𝐨𝐧𝐬𝐭𝐫𝐮𝐜𝐭𝐢𝐯𝐞𝐥𝐲, 𝐛𝐮𝐢𝐥𝐝 𝐬𝐨𝐥𝐮𝐭𝐢𝐨𝐧𝐬 𝐥𝐨𝐠𝐢𝐜𝐚𝐥𝐥𝐲, 𝐚𝐧𝐝 𝐬𝐭𝐫𝐞𝐧𝐠𝐭𝐡𝐞𝐧 𝐲𝐨𝐮𝐫 𝐩𝐫𝐨𝐛𝐥𝐞𝐦-𝐬𝐨𝐥𝐯𝐢𝐧𝐠 𝐦𝐢𝐧𝐝𝐬𝐞𝐭 — 𝐩𝐞𝐫𝐟𝐞𝐜𝐭 𝐟𝐨𝐫 𝐂𝐒𝐄𝐒, 𝐂𝐨𝐝𝐞𝐟𝐨𝐫𝐜𝐞𝐬, 𝐀𝐭𝐂𝐨𝐝𝐞𝐫, 𝐚𝐧𝐝 𝐈𝐂𝐏𝐂 𝐜𝐨𝐧𝐭𝐞𝐬𝐭𝐬.⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ ⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ 📘𝐍𝐨𝐭𝐞𝐬: ⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ https://github.com/yash7xm/cp_notes/blob/master/Digit%20DP/Counting%20Numbers.pdf⁣ ⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ 𝐂𝐨𝐝𝐞: https://github.com/yash7xm/cp-topics/blob/master/digit-dp/CountingNumbers.cpp⁣ ⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ 👉 𝐏𝐫𝐨𝐛𝐥𝐞𝐦 𝐋𝐢𝐧𝐤:⁣ https://cses.fi/problemset/task/2220/⁣ ⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ 🔗 𝐏𝐥𝐚𝐲𝐥𝐢𝐬𝐭: https://youtube.com/playlist?list=PLtfqa971vD5FqhXGZOkc9bmybbM9Mkxb4&si=1mplrS1YQ6LDEIz7⁣ ⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ ⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣💡 𝐏𝐞𝐫𝐟𝐞𝐜𝐭 𝐟𝐨𝐫:⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ - Competitive programmers⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ - Data structure & algorithms learners⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ - Coding interview prep⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ ⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ 📌 Watch this till the end to fully understand the intuition, not just the code.⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ ⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ 👉 Whether you’re a beginner or looking to strengthen your logical thinking, this course will help you 𝐭𝐡𝐢𝐧𝐤 𝐥𝐢𝐤𝐞 𝐚 𝐜𝐨𝐦𝐩𝐞𝐭𝐢𝐭𝐢𝐯𝐞 𝐩𝐫𝐨𝐠𝐫𝐚𝐦𝐦𝐞𝐫 𝐚𝐧𝐝 𝐝𝐞𝐬𝐢𝐠𝐧 𝐜𝐨𝐧𝐬𝐭𝐫𝐮𝐜𝐭𝐢𝐯𝐞 𝐬𝐨𝐥𝐮𝐭𝐢𝐨𝐧𝐬 𝐜𝐨𝐧𝐟𝐢𝐝𝐞𝐧𝐭𝐥𝐲 𝐢𝐧 𝐜𝐨𝐧𝐭𝐞𝐬𝐭𝐬.⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ ⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ 👋 𝐖𝐞𝐥𝐜𝐨𝐦𝐞 𝐭𝐨 𝐭𝐡𝐞 𝐜𝐡𝐚𝐧𝐧𝐞𝐥!⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ I create content on 𝐂𝐨𝐦𝐩𝐞𝐭𝐢𝐭𝐢𝐯𝐞 𝐏𝐫𝐨𝐠𝐫𝐚𝐦𝐦𝐢𝐧𝐠, 𝐃𝐚𝐭𝐚 𝐒𝐭𝐫𝐮𝐜𝐭𝐮𝐫𝐞𝐬 & 𝐀𝐥𝐠𝐨𝐫𝐢𝐭𝐡𝐦𝐬 (𝐃𝐒𝐀), 𝐚𝐧𝐝 𝐓𝐞𝐜𝐡𝐧𝐢𝐜𝐚𝐥 𝐈𝐧𝐭𝐞𝐫𝐯𝐢𝐞𝐰 𝐏𝐫𝐞𝐩𝐚𝐫𝐚𝐭𝐢𝐨𝐧.⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ If you find this video helpful, don’t forget to:⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ 👍 Like the video⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ 💬 Comment your doubts/questions (I reply to everyone!)⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ 🔔 Subscribe and turn on notifications to never miss upcoming tutorials⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ ⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ 📌 𝐂𝐨𝐧𝐧𝐞𝐜𝐭 𝐰𝐢𝐭𝐡 𝐦𝐞:⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ 🐦 X: https://x.com/Yash_Poonia_⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ 💼 LinkedIn: https://www.linkedin.com/in/yashpoonia/⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ 💻 GitHub: https://github.com/yash7xm⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ 🌐 Discord: https://discord.gg/dAp2PbKFpV⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ ⁣⁣⁣⁣⁣⁣⁣⁣⁣⁣ #DigitDP #CSES #DynamicProgramming #CompetitiveProgramming #DSA #Cplusplus #NumberDP #AlgorithmTutorial #CodingInterviewPrep #LearnDSA⁣ ⁣ ⁣