Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.
According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes v and w as the lowest node in T that has both v and w as descendants (where we allow a node to be a descendant of itself).”
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/ 3 5 For example, the lowest common ancestor (LCA) of nodes 2 and 8 is 6. Another example is LCA of nodes 2 and 4 is 2, since a node can be a descendant of itself according to the LCA definition.
/*** Definition for a binary tree node.* struct TreeNode {* int val;* TreeNode *left;* TreeNode *right;* TreeNode(int x) : val(x), left(NULL), right(NULL) {}* };*/class Solution {public:TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {if(root==p||root==q)return root;if(p->val>q->val)swap(p,q);if(root->val > p->val && root->val < q->val)return root;TreeNode *node;if(root->val > max(p->val,q->val))node=lowestCommonAncestor(root->left,p,q);if(root->val < min(p->val,q->val))node=lowestCommonAncestor(root->right,p,q);return node;}};
Lowest Common Ancestor of a Binary Search Tree
原文：http://www.cnblogs.com/zhxshseu/p/5284969.html