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#include 
   
    using namespace std;class Solution {    public:        TreeNode* lowestCommonAncestor(TreeNode* root, TreeNode* p, TreeNode* q) {            vector
    
      path_p = getPath(root, p);            vector
     
       path_q = getPath(root, q);            return findLastCommonAncestor(path_p, path_q);        }        vector
      
        getPath(TreeNode* node, TreeNode* target) {            vector
       
         path;            while (node != null && node != target) {                path.push_back(node);                if (node->left != null && node->left->val == target->val) {                    node = node->left;                } else if (node->right != null && node->right->val == target->val) {                    node = node->right;                } else {                    return path;                }            }            if (node != null) {                path.push_back(node);            }            return path;        }        TreeNode* findLastCommonAncestor(const vector
        
         & path_p, const vector
         
          & path_q) { int i = 0, j = 0; int len = 0; TreeNode* last = null; while (i < path_p.size() && j < path_q.size()) { if (path_p[i]->val == path_q[j]->val) { if (last != path_p[i]) { last = path_p[i]; } len++; i++; j++; } else { if (i < j) { i++; } else { j++; } } } return last; }};
         
        
       
      
     
    
   

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