# Basic CS-Data Structures [Redpine Infotech Placement]: Sample Questions 1 - 2 of 4

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## Question 1

Data Structures
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### Describe in Detail

Essay▾

Explain two problems related to in order and post order traversal.

## Inorder Traversal

• Algorithm:
• Traverse the left sub tree, i.e.. . , call inorder (left-sub tree)
• Visit the root
• Traverse the right sub tree, i.e.. . , call inorder (right-sub tree)
• Uses of Inorder
• Binary search trees, inorder traversal provides nodes in non-decreasing order.
• To get nodes of BST in non-increasing order, a variation of inorder traversal where inorder traversal is reversed can be used.

## Ex

• In order travel (left, root, right) : 4, 2,5, 1,3

## Post Order

• Algorithm:
• Traverse the left sub tree, i.e.. . , call Postorder (left-sub tree)
• Traverse the right sub tree, i.e.. . , call Postorder (right-sub tree)
• Visit the root.
• Use of Postorder:
• Used to delete the tree.
• To get the postfix expression of expression tree.

## Ex

Postorder (Left, Right, Root) : 4 5 2 3 1

## Question 2

Data Structures
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### Describe in Detail

Essay▾

Difference between re-entrance and recursion.

### Explanation

 Re-entrance Recursion A re-entrant function can be safely executed concurrently. A recursive function calls upon itself until a given condition is met Re-entrant function does operations like protect/lock static state. Recursive functions do not need to protect/lock access static state. Re-entrant function needs able to handle concurrent execution with different threads. Recursive able to handle entry while it is running, but it access controlled manner and not other thread. Re-entrant recursive functions are thread-safe. Recursive functions are not thread-safe Re-enter functions cannot modify static variables Recursion functions can modify static variables.

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