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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).”
_______6______
/ ___2__ ___8__
/ \ / 0 _4 7 9
/ 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.
1 class Solution {
2 public:
3 TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
4 if (p->val < root->val && q->val < root->val)
5 return lowestCommonAncestor(root->left, p, q);
6 if (p->val > root->val && q->val > root->val)
7 return lowestCommonAncestor(root->right, p, q);
8 return root;
9 }
10 };
Lowest Common Ancestor of a Binary Search Tree -- LeetCode
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原文地址：http://www.cnblogs.com/fenshen371/p/5168861.html
