Smallest window in a string containing all characters of another string .

**Problem statement**
Given two strings, S1 and S2, the task is to find the smallest substring in S1 containing all characters of S2 efficiently.
**Example:**
Given: S1="letsgrowmore" S2="srw"
Output= "sgrow"

Hey @Ayush7614 @Amit366 I would like to solve this issue using Sliding window Technique.

Language : I am interested to work in C++.

please assign this issue to me under LGM-SOC 21.