Update stack_queue_modification.md

Tushar0009 · web-flow · commit ecf52f787a50 · 2025-06-01T05:05:19.000+05:30
Added new Problem fron CSES Problem Set
diff --git a/src/data_structures/stack_queue_modification.md b/src/data_structures/stack_queue_modification.md
@@ -187,5 +187,6 @@ Since all operations with the queue are performed in constant time on average, t
 
 ## Practice Problems
 * [Queries with Fixed Length](https://www.hackerrank.com/challenges/queries-with-fixed-length/problem)
+* [Sliding Window Minimum](https://cses.fi/problemset/task/3221)
 * [Binary Land](https://www.codechef.com/MAY20A/problems/BINLAND)
 
