[LeetCode]Lowest Common Ancestor of a Binary Search Tree

Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST.

According to thedefinition 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 allowa node to be a descendant of itself).”

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For example, the lowest common ancestor (LCA) of nodes2and8is6. Another example is LCA of nodes2and4is2, since a node can be a descendant of itself according to the LCA definition.

［思路］根据二叉树的特点，最小的公共祖先就是在两个点值之间的根节点。特别要注意p，q两个点的大小是不确定的。

/** * 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) {int min = p->val>q->val?q->val:p->val;int max = p->val>q->val?p->val:q->val;while(true){if(root->val>=min&&root->val<=max)break;if(root->val<min){root = root->right;}if(root->val>max){root = root->left;}}return root;}};

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人，总是很难改正自己的缺点，