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) {}
 * };
 */
class Solution {
public:
    TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {
        queue<TreeNode* > pp;
        queue<TreeNode* > qq;
        search(root, p, pp);
        search(root, q, qq);
        TreeNode* res = NULL;
        while(pp.front()==qq.front())
        {
            res = pp.front();
            pp.pop();
            qq.pop();
        }
        return res;
    }
    void search(TreeNode* root, TreeNode* p, queue<TreeNode* > &pp)
    {
        TreeNode* tmp = root;
        while(tmp!=p)
        {
            pp.push(tmp);
            if(p->val > tmp->val)
                tmp = tmp->right;
            else
                tmp = tmp->left;
        }
        pp.push(p);
    }
};