You are given the root
of a binary tree with n
nodes. Each node is uniquely assigned a value from 1
to n
. You are also given an integer startValue
representing the value of the start node s
, and a different integer destValue
representing the value of the destination node t
.
Find the shortest path starting from node s
and ending at node t
. Generate step-by-step directions of such path as a string consisting of only the uppercase letters 'L'
, 'R'
, and 'U'
. Each letter indicates a specific direction:
'L'
means to go from a node to its left child node.'R'
means to go from a node to its right child node.'U'
means to go from a node to its parent node.
Return the step-by-step directions of the shortest path from node s
to node t
.
Example 1:
Input: root = [5,1,2,3,null,6,4], startValue = 3, destValue = 6 Output: "UURL" Explanation: The shortest path is: 3 → 1 → 5 → 2 → 6.
Example 2:
Input: root = [2,1], startValue = 2, destValue = 1 Output: "L" Explanation: The shortest path is: 2 → 1.
Constraints:
- The number of nodes in the tree is
n
. 2 <= n <= 105
1 <= Node.val <= n
- All the values in the tree are unique.
1 <= startValue, destValue <= n
startValue != destValue