Programming Interview Questions

Programming Interview Questions

Linked Lists

This is an extremely popular topic. I've had linked lists on every interview.
You must be able to produce simple clean linked list implementations quickly.

• Implement Insert and Delete for
  • singly-linked linked list
  • sorted linked list
  • circular linked list
  
  int Insert(node** head, int data)
int Delete(node** head, int deleteMe)

• Split a linked list given a pivot value
  void Split(node* head, int pivot, node** lt, node** gt)
• Find if a linked list has a cycle in it. Now do it without marking nodes.
• Find the middle of a linked list. Now do it while only going through the list once. (same solution as finding cycles)

Strings

• Reverse words in a string (words are separated by one or more spaces). Now do it in-place. By far the most popular string question!
• Reverse a string
• Strip whitespace from a string in-place
  void StripWhitespace(char* szStr)
• Remove duplicate chars from a string ("AAA BBB" -> "A B")
  int RemoveDups(char* szStr)
• Find the first non-repeating character in a string:("ABCA" -> B )
  int FindFirstUnique(char* szStr)

• More Advanced Topics:
  • You may be asked about using Unicode strings. What the interviewer is usually looking for is:
    • each character will be two bytes (so, for example, char lookup table you may have allocated needs to be expanded from 256 to 256 * 256 = 65536 elements)
    • that you would need to use wide char types (wchar_t instead of char)
    • that you would need to use wide string functions (like wprintf instead of printf)
  • Guarding against being passed invalid string pointers or non nul-terminated strings (using walking through a string and catching memory exceptions

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