chore: Update README with new problem

README.md

@@ -3,7 +3,7 @@
 ![repo stars](https://img.shields.io/github/stars/saulmaldonado/ds-and-algorithms?style=social)
 ![github followers](https://img.shields.io/github/followers/saulmaldonado?style=social)
 ![time since last commit](https://img.shields.io/github/last-commit/saulmaldonado/ds-and-algorithms)
-![number of problems](https://img.shields.io/badge/no.%20of%20problems-174-blue)
+![number of problems](https://img.shields.io/badge/no.%20of%20problems-175-blue)
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 > Data structures and algorithm problems with solution explanations and implementations for different languages
@@ -181,6 +181,10 @@
   <a href="strings/word-subsets">
     Word Subsets
   </a> - Medium
+</li><li>
+  <a href="strings/stamping-the-sequence">
+    Stamping The Sequence
+  </a> - Hard
 </li><li>
   <a href="strings/multiply-strings">
     Multiply Strings