二叉搜索树转排序双向链表

例如   10      /  \     5   16   ===>  3<->5<->6<->10<->12<->16    / \  /   3  6  12   使用递归的方式  

   1:  void build_dlist(node_t *node)

   2:  {

   3:      if (node->left) {

   4:          node_t * left = node->left;

   5:          while (left->right) {   //移动到双向链表的最右端，因为此处是链表的最大值。

   6:              left = left->right;

   7:          }

   8:          left->right = node;  //左子树链表最后节点指向父节点

   9:          node->left = left;   

  10:      }

  11:   

  12:      if (node->right) {

  13:          node_t * right = node->right;

  14:          while (right->left) {

  15:              right = right->left;

  16:          }

  17:          right->left = node;

  18:          node->right = right;

  19:      }

  20:  }

  21:   

  22:  void tree_to_list(node_t *node)

  23:  {

  24:      if (!node) {

  25:          return;

  26:      }

  27:      tree_to_list(node->left);

  28:      tree_to_list(node->right);

  29:      build_dlist(node);

  30:  }