通过后续遍历，可以减少重复访问

1 #include 
     
       2 #include 
      
        3 using namespace std; 4  5 struct BinaryTreeNode 6 { 7     int m_data; 8     BinaryTreeNode* m_left; 9     BinaryTreeNode* m_right;10 };11 12 int TreeDepth(BinaryTreeNode* pRoot)13 {14     if (pRoot==NULL)15     {16         return 0;17     }18     int nleft=TreeDepth(pRoot->m_left);19     int nright=TreeDepth(pRoot->m_right);20     return (nleft>nright)?(nleft+1):(nright+1);21 }22 23 bool IsBalance(BinaryTreeNode* pRoot,int *pDepth)24 {25     if (pRoot==NULL)26     {27         *pDepth=0;28         return true;29     }30     int left,right;31     if(IsBalance(pRoot->m_left,&left)&&IsBalance(pRoot->m_right),&right)32     {33         int diff=left-right;34         if (diff<=1&&diff>=-1)35         {36             *pDepth=1+(left>right)?left:right;37             return true;38         }39     }40     return false;41 }