CODEWITHSUNDEEP
algorithm
Albi Computers
Albi Computers

Reputation: 1

Binary tree preorder visit pseudocode

Have been searching on web for more than 5 hours and cant find a general BT Preorder visit pseudocode. Thanks in advance. I just find short pseudocodes like this 

 Algorithm postorder(T, v)
 Input: A binary tree T and a node v of T.
 Output: Depends on the action performed on a visit to a node.
  if T.hasLeft(v)
  postorder(T, T.left(v))   // recursively traverse left subtree
 if T.hasRight(v)
   postorder(T, T.right(v))  // recursively traverse right subtree
visit node v

Upvotes: 0

Views: 512

Answers (1)

aghast
aghast

Reputation: 15310

The difference between preorder, inorder, and postorder is simply the order in which the nodes are visited, relative to the children:

You posted this:

 Algorithm postorder(T, v)
 Input: A binary tree T and a node v of T.
 Output: Depends on the action performed on a visit to a node.

 if T.hasLeft(v)
   postorder(T, T.left(v))   // recursively traverse left subtree
 if T.hasRight(v)
   postorder(T, T.right(v))  // recursively traverse right subtree
 visit node v

To change among the behaviors, change the order of execution. Here's some generic code:

AnyOrder:

AnyOrder(T, v, order)

    if order is 'pre'
        visit(v)

    AnyOrder(T, T.left(v), order)

    if order is 'in'
        visit(v)

    AnyOrder(T, T.right(v), order)

    if order is 'post'
        visit(v)

Upvotes: 1

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