Create README.md

Author: lyushher

day-27/README.md

@@ -0,0 +1,45 @@
+# Day 27 
+
+## ⭐️ Relative Ranks – 27.1
+### 🔗 Problem
+[LeetCode #506 – Relative Ranks](https://leetcode.com/problems/relative-ranks/)
+
+### 🧠 Core Idea
+Pair each score with its original index, sort scores in descending order, and assign medals to the top three athletes ("Gold Medal", "Silver Medal", "Bronze Medal").
+For the remaining athletes, assign their rank number as a string.
+Place the results back into their original positions to preserve input order.
+
+### 📊 Example
+Input: `score = \[10,3,8,9,4]`
+
+Output: \["Gold Medal","5","Bronze Medal","Silver Medal","4"]
+
+### ⏱️ Complexity
+- Time: O(n log n) – Sorting the scores
+
+- Space: O(n) – For the result array and index pairs
+
+👉 See full code in [relative_ranks.py](https://github.com/lyushher/LeetCode-Python-Easy-DSA/blob/main/day-27/relative_ranks.py)
+
+---
+
+## ⭐️ Find the Difference – 27.2
+### 🔗 Problem
+[LeetCode #389 – Find the Difference](https://leetcode.com/problems/find-the-difference/)
+
+### 🧠 Core Idea
+The extra character in string `t` can be found by XORing all characters in `s` and `t`. Matching characters cancel out, leaving only the added character.
+Alternatively, compute the difference of ASCII sums of `t` and `s`.
+Both methods work in linear time and constant space.
+
+### 📊 Example
+Input: s = "abcd", t = "abcde"
+
+Output: "e" → Because "e" is the extra character in `t`
+
+### ⏱️ Complexity
+- Time: O(n) – One pass through both strings
+
+- Space: O(1) – Only a few variables used
+
+👉 See full code in [find_the_difference.py](https://github.com/lyushher/LeetCode-Python-Easy-DSA/blob/main/day-27/find_the_difference.py)