标签：
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.
思路：
利用二叉树的性质，根节点的值小于左子树的值而小于右子树的值，因此可以根据这一性质，递归判断p,q结点在哪一棵子树中。
解法：
1 /* 2 public class TreeNode 3 { 4 int val; 5 TreeNode left; 6 TreeNode right; 7 8 TreeNode(int x) 9 { val = x; } 10 } 11 */ 12 13 public class Solution 14 { 15 public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) 16 { 17 if(root == null || p == null || q == null) 18 return null; 19 20 if(p.val < root.val && q.val < root.val) 21 return lowestCommonAncestor(root.left, p, q); 22 else if(p.val > root.val && q.val > root.val) 23 return lowestCommonAncestor(root.right, p, q); 24 else 25 return root; 26 } 27 }
LeetCode 235 Lowest Common Ancestor of a Binary Search Tree
标签：
原文地址：http://www.cnblogs.com/wood-python/p/5839178.html
