235. Lowest Common Ancestor of a Binary Search Tree

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
static int wing=[]()
{
    std::ios::sync_with_stdio(false);
    cin.tie(NULL);
    return 0;
}();

class Solution 
{
public:
    TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) 
    {
        int ip=p->val;
        int iq=q->val;
        int imax=max(ip,iq);
        int imin=ip+iq-imax;
        TreeNode *h=root;
        while((imin>h->val)||(imax<h->val))
            h=(imin>h->val)? h->right:h->left;
        return h;        
    }
};

二叉排序树找两个节点的最近祖先，从根节点开始，第一个把两个给定节点分开的，就是最近祖先。