leetcode 235 Lowest Common Ancestor of a Binary Search Tree（难易度：Easy）

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 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 allowa 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.

代码：

/** * Definition for a binary tree node. * struct TreeNode { *     int val; *     struct TreeNode *left; *     struct TreeNode *right; * }; */struct TreeNode* lowestCommonAncestor(struct TreeNode* root, struct TreeNode* p, struct TreeNode* q) {    struct TreeNode *cur = root;    while(true)    {        if(cur->val > p->val && cur->val > q->val)            cur = cur->left;        else if(cur->val < p->val && cur->val < q->val)            cur = cur->right;        else            return cur;    }}

原题地址：https://leetcode.com/problems/lowest-common-ancestor-of-a-binary-search-tree/