题目：
Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.
Analysis
This problem can be solved by using BST property, i.e., left < parent < right for each node. There are 3 cases to handle.
1 public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) 2 { 3 TreeNode m = root; 4 5 if(m.val>p.val&&m.val<q.val) return m; 6 if(m.val>p.val&&m.val>q.val) 7 { 8 return lowestCommonAncestor(root.left,p,q); 9 } 10 if(m.val<p.val&&m.val<q.val) 11 { 12 return lowestCommonAncestor(root.right,p,q); 13 } 14 15 return root; 16 }
reference：http://www.programcreek.com/2014/07/leetcode-lowest-common-ancestor-of-a-binary-search-tree-java/
Lowest Common Ancestor of a Binary Search Tree
原文：http://www.cnblogs.com/hygeia/p/4770500.html