重建二叉树

/*    重建二叉树    pre  1,2,4,7,3,5,6,8    in   4,7,2,1,5,3,8,6*/struct BinTree{    int m_nValue;    BinTree* m_pLeft;    BinTree* m_pRight;    BinTree(int x) :        m_nValue(x), m_pLeft(NULL), m_pRight(NULL)    {}    BinTree(int x,BinTree* l,BinTree* r) :        m_nValue(x), m_pLeft(l), m_pRight(r)    {}};BinTree* ConstructCore(int* startpre, int *endpre, int* startin, int* endin){    int rootvalue = startpre[0];    BinTree* root = new BinTree(rootvalue);    if (startpre == endpre)    {        if (startin == endin && *startpre == *startin)            return root;        else            throw std::exception("invalid input");    }    int *rootIn = startin;    while (rootIn <= endin && *rootIn != rootvalue)        ++rootIn;    if (rootIn == endin && *rootIn != rootvalue)        throw std::exception("invalid input");    int LeftLength = rootIn - startin;    int* LeftPreorderEnd = startpre + LeftLength;    if (LeftLength > 0)    {        root->m_pLeft = ConstructCore(startpre + 1, LeftPreorderEnd, startin, rootIn - 1);    }    if (LeftLength < endpre - startpre)    {        root->m_pRight = ConstructCore(LeftPreorderEnd + 1, endpre, rootIn + 1, endin);    }    return root;}BinTree* Construct(int* pre, int* in, int length){    if (pre == NULL || in == NULL || length <= 0)        return NULL;    return ConstructCore(pre, pre + length - 1, in, in + length - 1);}//void test()//{//  int pre[8] = { 1,2,4,7,3,5,6,8 };//  int in[8] = { 4,7,2,1,5,3,8,6 };////  BinTree* root = Construct(pre, in, 8);//  getchar();//}