Data Structure and Algorithm Lesson 2.pptx

Editor's Notes

• #3: The dream of every programmer is to become not just a good, but also a great programmer. We all want to achieve our goals and to achieve our goals, we must have a great plan with us. In this context, we have decided to provide a complete guide for Arrays interview preparation, which will help you to tackle the problems that are mostly asked in the interview, such as What is an Array, What is Array in C language, How do you initialize an Array in C, How to sort an Array, etc. We have also covered the topics such as Top Theoretical interview questions and Top interview coding questions in this complete guide for Array interview preparation. It’s one of the most popular and simple data structures and is often used to implement other data structures. Each item in an array is indexed starting with 0.
• #7: Unlike arrays, linked lists do not have a fixed size, and their elements are not stored in contiguous memory locations. Instead, each element (node) points to the next one, forming a chain-like structure.
• #15: In this example: We define a structure Node to represent a node in a linked list. It contains an integer data field and a pointer to the next node. The createNode() function dynamically allocates memory for a new node using malloc(). If memory allocation fails, it prints an error message and exits the program. In the main() function, we initialize an empty linked list and insert nodes dynamically using the createNode() function. After printing the elements of the linked list, we free the memory allocated for each node using the free() function to prevent memory leaks. This example demonstrates how linked lists are used in conjunction with dynamic memory allocation functions like malloc() and free() to manage memory dynamically in C programs. ``` 1. **`#include <stdio.h>` and `#include <stdlib.h>`**: - These are preprocessor directives in C. - `#include <stdio.h>` includes the standard input/output library, which provides functions like `printf()` and `scanf()`. - `#include <stdlib.h>` includes the standard library, which provides functions like memory allocation (`malloc()`, `calloc()`, `realloc()`) and memory deallocation (`free()`). 2. **`struct Node { ... };`**: - This defines a structure named `Node`. - It contains two members: `int data` (to store integer data) and `struct Node* next` (a pointer to the next node in the linked list). 3. **`struct Node* createNode(int data) { ... }`**: - This is a function named `createNode()` that returns a pointer to a newly allocated `Node` structure. - It takes an integer parameter `data`, which represents the data to be stored in the node. - Inside the function: - It allocates memory for a new `Node` structure using `malloc(sizeof(struct Node))`. If memory allocation fails (`malloc()` returns `NULL`), it prints an error message and exits the program using `exit(1)`. - It assigns the input `data` to the `data` member of the newly created node. - It initializes the `next` pointer of the node to `NULL`, indicating that it's the last node in the list. - Finally, it returns a pointer to the newly created node. Overall, this code defines a basic structure for a singly linked list node (`Node`) and a function to dynamically create new nodes (`createNode()`). The inclusion of standard libraries (`<stdio.h>` and `<stdlib.h>`) provides necessary functionality for input/output operations and memory allocation/deallocation.
• #16: int main() { // Create the head of the linked list and initialize it with a node containing data 10 struct Node* head = createNode(10); // Create the second node with data 20 and attach it to the head node head->next = createNode(20); // Create the third node with data 30 and attach it to the second node head->next->next = createNode(30); // Print the elements of the linked list printf("Linked List: "); for (struct Node* current = head; current != NULL; current = current->next) printf("%d -> ", current->data); printf("NULL\n"); // Free memory allocated for the linked list nodes for (struct Node* current = head; current != NULL;) { // Store the current node in a temporary variable struct Node* temp = current; // Move to the next node current = current->next; // Free the memory allocated for the current node free(temp
• #21: 4. Applications of Stacks: Expression Evaluation: Stacks are commonly used in evaluating arithmetic expressions, such as infix, postfix, and prefix expressions. Operators and operands are pushed onto the stack, and operations are performed based on their precedence and associativity. Function Calls: Stacks are used in function call mechanisms, such as maintaining the call stack in recursive function calls. When a function is called, its local variables and the return address are pushed onto the stack, and they are popped off when the function returns. Backtracking Algorithms: Stacks are utilized in backtracking algorithms, such as depth-first search (DFS), to store the state of exploration. During backtracking, the algorithm pops elements from the stack to backtrack to previous states and explore other paths.