Lecture Notes: Introduction to Programming with Striver

Introduction

Presenter: Striver
Platform: Interview preparation website and YouTube channel
Target Audience: Programmers preparing for interviews (3-6 months left)
Main Resources: Striver's SD Sheet (191 curated problems)
New Resource: Striver's A to Z DSA course/sheet
- 455 steps with problem links and videos for hard topics

Recommended Initial Steps for Beginners

Basics of DS Algo: Ensure understanding before starting
Choose a programming language: C++, Java, Python, JavaScript
- Master one language
  - Previous video covers C++ vs Java

Starting with C++ Basics

Skeleton of C++ code: #include, int main, {}, return 0;
Input/Output Libraries: #include<iostream> for input/output
- Other libraries: math.h for math functions, string for string functions

C++ Code Example

#include <iostream>
using namespace std;

int main() {
    cout << "Hello, world!" << endl;
    return 0;
}

Detailed C++ Concepts

Basic Structure

Input/Output: cin, cout
Escaping Characters: \n, endl
Using Namespaces: using namespace std;

Data Types

Integer: int, long, long long
Floating Point: float, double
String: string, getline
Character: char
Universal Library Inclusion: #include<bits/stdc++.h>

Conditional Statements

If-Else: Basic decision-making
Nested If-Else: For complex conditions
Examples: Age check, grading system

Switch Statements

Purpose: Alternative to multiple if-else
Syntax: switch (variable) { case 1: ... break; case 2: ... break; ... default: ... }

Arrays and Strings

1D Arrays: Used for storing similar data types
2D Arrays: For Matrix-like structures
Strings: Sequence of characters
Accessing Elements: Using indices

Loops

For Loop

Syntax: for (initialization; condition; increment/decrement) { ... }
Nested For Loops: Often used in pattern problems

While Loop

Syntax: while (condition) { ... }
Do-While Loop: Guaranteed to execute at least once, do { ... } while (condition);

Functions

Introduction

Purpose: Modularize code, improve readability, reuse code
Types:
- Void Functions (no return value)
- Functions with return values
- Parameterized Functions
- Non-Parameterized Functions

Detailed Example

Void Function:

void printName() {
    cout << "Striver" << endl;
}

int main() {
    printName();
    return 0;
}

Parameterized Function:

void printName(string name) {
    cout << name << endl;
}

int main() {
    string name = "Striver";
    printName(name);
    return 0;
}

Return Function:

int sum(int num1, int num2) {
    return num1 + num2;
}

int main() {
    int result = sum(5, 10);
    cout << result << endl;
    return 0;
}

Pass by Value vs Pass by Reference

Pass by Value: Original data is not modified
- Copies of values are passed to functions
Pass by Reference: Original data is modified
- Actual memory address is passed to functions
Example of Pass by Reference:

void doSomething(int &num) {
    num += 5;
}

int main() {
    int number = 10;
    doSomething(number);
    cout << number << endl; // Output will be 15
    return 0;
}

Arrays and Functions

Arrays are passed by reference: Modifications in functions reflect outside
Example:

void modifyArray(int arr[], int size) {
    for(int i = 0; i < size; i++) {
        arr[i] += 100;
    }
}

int main() {
    int arr[5] = {1, 2, 3, 4, 5};
    modifyArray(arr, 5);
    for(int i = 0; i < 5; i++) {
        cout << arr[i] << " "; // Outputs: 101 102 103 104 105
    }
    return 0;
}

Conclusion

Upcoming Topics: In-depth time complexity
Next Steps: Watch C++ STL video for more insights
Action Items: Like, subscribe, and follow Striver on social media for updates on the DSA playlist.