Editing Treap (section)

==== Find sum, minimum or maximum in a given range ====
To perform this calculation we will proceed as follows:

* First we will create an additional field F to store the value of the target function for the range represented by that node. we will create a function that calculates the value F based on the values of the L and R children of the node. We will call this target function at the end of all functions that modify the tree, ''i.e.'', split and join.  
* Second we need to process a query for a given range [A..B]: We will call the '''s''plit''''' function twice and split the treap into <math>T1</math> which contains <math>\{1..A-1\}
</math>, <math>T2
</math> which contains <math>\{A..B\}
</math>, and '''''<math>T3</math>''''' which contains <math>\{B+1..n\}
</math>. After the query is answered we will call the '''''join''''' function twice to restore the original treap.