Shortest Path Between Nodes

Problem

Given the root of a binary tree and two values start and dest, calculate the minimum number of steps required to move from the node with start to the node with dest. The path must follow the tree structure.

Examples

shortestPath([1,2,3], 2, 3)
// returns 2
// Moving from node 2 to 1 takes one step
// and from node 1 to 3 takes another step
// totaling two steps.