Understanding the stateless root to leaf path pattern

A root-to-leaf path in a binary tree is a path made up of nodes starting from the root node and ending at a leaf node, and there are as many root-to-leaf paths in a binary tree as there are leaves. Many binary tree problems require us to find, for all root-to-leaf paths, the aggregated value of a function f over some or all nodes in a root-to-leaf path. Some problems go even further to find the aggregated value of some other function g over all aggregated values of all the root-to-leaf paths and return a single result.

There are two ways to solve this problem: one requires some shared state to be maintained, while the other is completely stateless. The choice between these options depends on the function f and g and the complexity of the problem. Depending on the functions f and g, the problem can be solved using the stateless root-to-leaf path technique.

In this lesson, we will learn more about using the stateless root-to-leaf path technique to solve binary tree problems and how to identify a problem as a root-to-leaf path pattern problem.

The stateless root to leaf path technique