Lowest Common Ancestor of a Binary Search Tree
Difficulty: MediumTopic: TreeDepth-First SearchBinary Search TreeBinary TreeLeetcode:235.Lowest Common Ancestor of a Binary Search TreeGiven a binary search tree (BST), find the lowest common ancestor (LCA) node of two given nodes in the BST.
According to the definition of LCA on Wikipedia (opens in a new tab): “The lowest common ancestor is defined between two nodes p and q as the lowest node in T that has both p and q as descendants (where we allow a node to be a descendant of itself).”
Example 1:
Input: root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 8
Output: 6
Explanation: The LCA of nodes 2 and 8 is 6.
Example 2:
Input: root = [6,2,8,0,4,7,9,null,null,3,5], p = 2, q = 4
Output: 2
Explanation: The LCA of nodes 2 and 4 is 2, since a node can be a descendant of itself according to the LCA definition.
Example 3:
Input: root = [2,1], p = 2, q = 1
Output: 2
Constraints:
- The number of nodes in the tree is in the range
[2, 105]. -109 <= Node.val <= 109- All
Node.valare unique. p != qpandqwill exist in the BST.
Solution
write solution in here
/**
* @param {TreeNode} root
* @param {TreeNode} p
* @param {TreeNode} q
* @return {TreeNode}
*/
var lowestCommonAncestor = function (root, p, q) {
let max = Math.max(p.val, q.val),
min = Math.min(p.val, q.val)
if (root.val === min || root.val === max) return root
if (root.val < max && root.val > min) return root
return lowestCommonAncestor(min > root.val ? root.right : root.left, p, q)
};