Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>A blatant copy and paste from <a href="http://forums.sun.com/thread.jspa?forumID=426&amp;threadID=667512" rel="nofollow noreferrer">Sun's (Oracle now, I guess...) forum</a>:</p> <blockquote> <blockquote> <p><strong>Question:</strong> <br /> <em>Can anybody help me on how to construct Binary tree from inorder and postorder traversals,i just want to know the algorithm so that i can apply it.</em></p> </blockquote> <p><strong>Answer:</strong><br /> Let <code>p_1</code>, <code>p_2</code> <code>...</code> <code>p_n</code> be the postorder traversal and let <code>i_1</code>, <code>i_2</code> <code>...</code> <code>i_n</code> be the inorder traversal. From the postorder traversal we know that the root of the tree is <code>p_n</code>. Find this element in the inorder traversal, say <code>i_1</code>, <code>i_2</code> <code>...</code> <code>i_k-1</code> <code>p_n</code> <code>i_k+1</code> <code>...</code> <code>i_n</code>. From the inorder traversal we find all the elements in the left subtree, i.e. <code>i_1</code>, <code>i_2</code> <code>...</code> <code>i_k-1</code> and in the right subtree, i.e. <code>i_k+1</code> <code>...</code> <code>i_n</code> respectively.</p> <p>Remove element <code>p_n</code> (and element <code>i_k</code> <code>==</code> <code>p_n</code>). Find the rightmost element <code>p_j</code> in <code>p_1</code>, <code>p_2</code> <code>...</code> <code>p_j</code> <code>...</code> <code>p_n-1</code> where <code>p_j</code> is an element in <code>i_1</code>, <code>i_2</code> ... <code>i_k-1</code>. This is the root of the left subtree of the original tree. Split <code>p_1</code>, <code>p_2</code> <code>...</code> <code>p_j</code> and <code>p_j+1</code> ... <code>p_n-1</code> and <code>i_1</code>, <code>i_2</code> <code>...</code> <code>i_k-1</code> and <code>i_k+1</code> <code>...</code> <code>i_n</code>. Now you have two subsequences representing the postorder and inorder traversal of the two subtrees of the original tree.</p> </blockquote> <p>Author: <a href="http://forums.sun.com/profile.jspa?userID=431408" rel="nofollow noreferrer">JosAH</a>.</p> <p>I've implemented the algorithm once following Jos' instructions, and it worked perfectly!</p>
    singulars
    1. This table or related slice is empty.
    1. POConstruct a Tree
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USBart Kiers
    1. USBart Kiers
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COIt is too time consuming to find rightmost element p_j in p_1 ~ p_n-1 while it is also in i_1~i_k-1. It takes O(n^2) time. Actually, after removing p_n, and find its position in i_1~i_n. We already know the position of p_j. This is because we already know the count of nodes in its left and right subtree, which could be gotten by counting the elements after p_n in i_1~i_n. By this, we could easily find the place to split p_1~p_n-1
      singulars
      1. PO
      1. USibread
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload