A dictionary is a general-purpose data structure that associates keys with values, allowing retrieval of values based on keys. It consists of key-value pairs where keys must be unique and comparable. The document discusses standard operations for dictionaries and their time complexities depending on the implementation method.

1. Dictionary Data Structure

2. Dictionary Data Structure
Definition : A dictionary is defined as a general-purpose
data structure for storing a group of objects. A dictionary is
associated with a set of keys and each key has a single
associated value. When presented with a key, the dictionary
will simply return the associated value.

3. Dictionary Example
For example, the students list in the classroom could be represented as dictionary with
Student’s rollno and name. rollno is key and name is value.
Students = {501: “Kiran”,
502: “Raju”,
503: “Praveen”};

4. Dictionary ADT
Data:
• Set of (key, value) pairs
• keys are mapped to values
• keys must be comparable
• keys must be unique
Standard Operations:
• insert(key, value)
• find(key)
• delete(key)

5. Dictionary Implementation using Linear List
struct DictNode{
int key;
char value[20];
struct DictNode *link;
};
Value link
Key

6. Dictionary Implementation using Linear List
501 Raju
Value link
Key
502 Kumar 503 Pravee
n
NULL
start

7. Dictionary Time complexity
• Unordered
• search : O(n) , insert : O(1), delete : O(n)
• Ordered Array
• search : O(logn) , insert : O(n), delete : O(n)
• Ordered Linked List
• search : O(n) , insert : O(n), delete : O(n)

8. Thank You