With the help of TopCoder Tutorial and this post, I was able to understand the basic idea of how basic the cumulative frequency sum is stored in the left subtree of a BIT node.I was successfully able to understand the point update and range query for which BIT is famous for.
Then I came across this post which explained the range update and point query.Applying the idea which I understood for the point update,I couldn't understand the range update.
Is the idea for range update/point query different from point update/range query? Please help with the intuition behind range update/point query.