Update README with LeetCode Daily Challenge

Author: jeremymanning

README.md

@@ -25,6 +25,7 @@ This means you'll always find an AI-generated solution to compare with or learn
 | December 3, 2025 | [3625](https://leetcode.com/problems/count-number-of-trapezoids-ii/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/3625) | 🔴 Hard |
 | December 4, 2025 | [2211](https://leetcode.com/problems/count-collisions-on-a-road/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/2211) | 🟡 Medium |
 | December 5, 2025 | [3432](https://leetcode.com/problems/count-partitions-with-even-sum-difference/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/3432) | 🟢 Easy |
+| December 6, 2025 | [3578](https://leetcode.com/problems/count-partitions-with-max-min-difference-at-most-k/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/3578) | 🟡 Medium |
 
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