organization in the src structure, modification of README

src/EXTRA_INTERVIEW_PROBLEMS/advanced/lru_cache.py

@@ -0,0 +1,18 @@
+#!/usr/bin/env python3
+
+__author__ = "bt3"
+
+
+from functools import lru_cache
+
+
+@lru_cache(maxsize=20)
+def fib(n):
+    if n < 2:
+        return n
+    return fib(n-1) + fib(n-2)
+
+
+if __name__ == '__main__':
+    print([fib(n) for n in range(10)])
+    print(fib.cache_info())