void BTreeToDoubleLinkList(Node *pRoot, Node *&pFirst, Node *&pLast){    if (!pRoot)    {        pFirst = NULL;        pLast = NULL;        return;    }    Node *pFirstLeft = NULL;    Node *pLastLeft = NULL;    Node *pFirstRight = NULL;    Node *pLastRight = NULL;    if (!pRoot->pLeft)        pFirst = pRoot;    else {        BTreeToDoubleLinkList(pRoot->pLeft, pFirstLeft, pLastLeft);        pFirst = pFirstLeft;        pRoot->pLeft = pLastLeft;        pLastLeft->pRight = pRoot;    }    if (!pRoot->pRight)        pLast = pRoot;    else {        BTreeToDoubleLinkList(pRoot->pRight, pFirstRight, pLastRight);        pLast = pLastRight;        pRoot->pRight = pFirstLeft;        pFirstRight->pLeft = pRoot;    }}

 

 

 

 

 

 

 

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