Lowest Common Ancestor of a Binary Tree（迭代法）

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

According to the definition of LCA on Wikipedia: “The lowest common ancestor is defined between two nodes p and q as the lowest node in T that has both p and q as descendants (where we allow a node to be a descendant of itself).”

/**
 * 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) {
        if(root==NULL||root==p||root==q)
            return root;
        list pathp;
        list pathq;
        getPath(root,p,pathp);
        getPath(root,q,pathq);
        TreeNode *ret=NULL;
        ret=getNode(pathp,pathq);
        return ret;
    }
    bool getPath(TreeNode *root,TreeNode *h,list &path)
    {
        if(root==h)
            return true;
        path.push_back(root);
        if(root->left)
        {
            path.push_back(root->left);
            if(getPath(root->left,h,path))
                return true;
            path.pop_back();
        }
        if(root->right)
        {
            path.push_back(root->right);
            if(getPath(root->right,h,path))
                return true;
            path.pop_back();
        }
        path.pop_back();
        return false;
    }
    TreeNode* getNode(list &pathp,list &pathq)
    {
        auto i1=pathp.begin();
        auto i2=pathq.begin();
        TreeNode *ret=NULL;
        while(i1!=pathp.end()&&i2!=pathq.end())
        {
            if(*i1==*i2)
                ret=*i1;
            i1++;
            i2++;
        }
        return ret;
    }
};