Update README.

Author: deepakhb2

README.md

@@ -1,6 +1,31 @@
 # Data structures and algorithms
 The data structures and algorithms are implemented using ruby. I have also added few interview problems and I update this list as I work on problems.
 
+## Content 
+
+### Data Structures
+1. Arrays
+2. Hash
+3. Stacks
+4. Queues
+5. Trees
+6. Linked Lists
+7. Graphs
+
+### Algorithms
+1. Recursions
+2. Sorting
+3. Searching
+4. Dijkstras
+5. Bellmanford
+
+### Interview Questions
+Needs to be improved.
+
+### Problems
+...
+
+## Run it online
 This can be run on repl.it by clicking below badge. On repl.it click on Run button to see the output for bubble sort and you understand how to run other ruby files.
 
 [![Run on Repl.it](https://repl.it/badge/github/deepakhb2/data-structures-and-algorithm)](https://repl.it/github/deepakhb2/data-structures-and-algorithm)