🚀 DSA with C – Day 3: Bubble Sort & Binary Search

 

🎯 Goal:

• Learn Bubble Sort and sort arrays.

• Understand how Binary Search works.

• Compare Linear vs Binary Search.

• Practice problems on sorted arrays.

---

🧠 Theory

✅ Bubble Sort:

• Repeatedly compares adjacent elements and swaps them if they’re in the wrong order.

• Worst-case time complexity: O(n²)

• Best-case (already sorted): O(n) with optimization

---

👨‍💻 Bubble Sort in C

#include <stdio.h>

int main() {
    int arr[100], n, i, j, temp;

    printf("Enter number of elements: ");
    scanf("%d", &n);
    printf("Enter %d elements:\n", n);
    for (i = 0; i < n; i++)
        scanf("%d", &arr[i]);

    // Bubble Sort
    for (i = 0; i < n - 1; i++) {
        int swapped = 0;
        for (j = 0; j < n - i - 1; j++) {
            if (arr[j] > arr[j + 1]) {
                // Swap
                temp = arr[j];
                arr[j] = arr[j + 1];
                arr[j + 1] = temp;
                swapped = 1;
            }
        }
        if (swapped == 0)
            break; // Already sorted
    }

    printf("Sorted array:\n");
    for (i = 0; i < n; i++)
        printf("%d ", arr[i]);

    return 0;
}

---

✅ Binary Search:

• Efficient searching technique on sorted arrays.

• Time Complexity: O(log n)

• Repeatedly divide the array and compare with middle element.

---

👨‍💻 Binary Search in C

#include <stdio.h>

int binarySearch(int arr[], int n, int key) {
    int low = 0, high = n - 1, mid;

    while (low <= high) {
        mid = (low + high) / 2;

        if (arr[mid] == key)
            return mid;
        else if (arr[mid] < key)
            low = mid + 1;
        else
            high = mid - 1;
    }

    return -1; // Not found
}

int main() {
    int arr[100], n, key;

    printf("Enter number of elements: ");
    scanf("%d", &n);
    printf("Enter %d sorted elements:\n", n);
    for (int i = 0; i < n; i++)
        scanf("%d", &arr[i]);

    printf("Enter element to search: ");
    scanf("%d", &key);

    int result = binarySearch(arr, n, key);
    if (result == -1)
        printf("Element not found.\n");
    else
        printf("Element found at index %d.\n", result);

    return 0;
}

---

🔁 Linear vs Binary Search

Feature	Linear Search	Binary Search
Time Complexity	O(n)	O(log n)
Sorted Array Required	❌ No	✅ Yes
Speed	Slower	Faster for large data
Approach	Scan all elements	Divide & Conquer

🧪 Practice Problems:

1. Sort an array using Bubble Sort in descending order.

2. Count how many swaps were done during Bubble Sort.

3. Use Binary Search to find the number of occurrences of a given element.

4. If not found in Binary Search, return where it should be inserted.

---

📘 Homework for Day 3:

• Implement recursive Binary Search.

• Write a program that first sorts using Bubble Sort and then searches using Binary Search.

• LeetCode problem suggestion: Search Insert Position

---

📅 Day 3 Summary

• ✅ Learned Bubble Sort (with optimization)

• ✅ Implemented Binary Search (iterative)

• ✅ Practiced comparing search algorithms

✅ Solution Implement Both Linear and Binary Search Day 3 DSA with Java

🔹 Linear Search in Java

public class LinearSearch {
    public static int linearSearch(int[] arr, int key) {
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] == key) return i;
        }
        return -1; // Not found
    }

    public static void main(String[] args) {
        int[] arr = {5, 3, 8, 2, 9};
        int key = 8;
        int index = linearSearch(arr, key);
        System.out.println("Element found at index: " + index);
    }
}

---

🔹 Binary Search in Java (Iterative)

public class BinarySearch {
    public static int binarySearch(int[] arr, int key) {
        int start = 0, end = arr.length - 1;
        while (start <= end) {
            int mid = start + (end - start) / 2;
            if (arr[mid] == key) return mid;
            else if (arr[mid] < key) start = mid + 1;
            else end = mid - 1;
        }
        return -1;
    }

    public static void main(String[] args) {
        int[] arr = {1, 3, 5, 7, 9};
        int key = 5;
        int index = binarySearch(arr, key);
        System.out.println("Element found at index: " + index);
    }
}

---

✅ 2. LeetCode Problems

🔸 Search Insert Position

Problem: Return the index if the target is found. If not, return the index where it would be inserted.

public class SearchInsertPosition {
    public static int searchInsert(int[] nums, int target) {
        int low = 0, high = nums.length - 1;
        while (low <= high) {
            int mid = low + (high - low) / 2;
            if (nums[mid] == target) return mid;
            else if (nums[mid] < target) low = mid + 1;
            else high = mid - 1;
        }
        return low;
    }

    public static void main(String[] args) {
        int[] nums = {1, 3, 5, 6};
        int target = 2;
        System.out.println("Insert position: " + searchInsert(nums, target));
    }
}

---

🔸 First Bad Version

Assume isBadVersion(version) API exists.

public class FirstBadVersion {
    static int bad = 4; // Let's assume version 4 is the first bad version

    public static boolean isBadVersion(int version) {
        return version >= bad;
    }

    public static int firstBadVersion(int n) {
        int low = 1, high = n;
        while (low < high) {
            int mid = low + (high - low) / 2;
            if (isBadVersion(mid)) high = mid;
            else low = mid + 1;
        }
        return low;
    }

    public static void main(String[] args) {
        System.out.println("First bad version: " + firstBadVersion(10));
    }
}

---

🌱 3. Explore: Lower Bound & Upper Bound

These are binary search variants often used in competitive programming.

🔸 Lower Bound (First element ≥ target)

public static int lowerBound(int[] arr, int target) {
    int low = 0, high = arr.length;
    while (low < high) {
        int mid = low + (high - low) / 2;
        if (arr[mid] < target) low = mid + 1;
        else high = mid;
    }
    return low; // returns the index
}

🔸 Upper Bound (First element > target)

public static int upperBound(int[] arr, int target) {
    int low = 0, high = arr.length;
    while (low < high) {
        int mid = low + (high - low) / 2;
        if (arr[mid] <= target) low = mid + 1;
        else high = mid;
    }
    return low; // returns the index
}

You can test both with:

int[] arr = {1, 3, 3, 5, 7};
System.out.println("Lower Bound of 3: " + lowerBound(arr, 3)); // Output: 1
System.out.println("Upper Bound of 3: " + upperBound(arr, 3)); // Output: 3

🚀 Day 3: Searching Algorithms in Java

🎯 Goals:

• Understand Linear Search and Binary Search

• Learn when and how to use each

• Solve real interview problems using searching techniques

---

🔍 1. Linear Search

📘 Definition:

Linearly checks each element one by one. Used when the array is unsorted.

✅ Code Example:

public static int linearSearch(int[] arr, int key) {
    for (int i = 0; i < arr.length; i++) {
        if (arr[i] == key) return i;
    }
    return -1; // Not found
}

---

🧠 2. Binary Search

📘 Definition:

Used on sorted arrays. It divides the search space in half each time — O(log N) time complexity.

✅ Code (Iterative Approach):

public static int binarySearch(int[] arr, int key) {
    int start = 0, end = arr.length - 1;
    while (start <= end) {
        int mid = start + (end - start) / 2;

        if (arr[mid] == key) return mid;
        else if (arr[mid] < key) start = mid + 1;
        else end = mid - 1;
    }
    return -1;
}

✅ Code (Recursive Approach):

public static int binarySearchRec(int[] arr, int key, int start, int end) {
    if (start > end) return -1;

    int mid = start + (end - start) / 2;
    if (arr[mid] == key) return mid;
    else if (arr[mid] < key) return binarySearchRec(arr, key, mid + 1, end);
    else return binarySearchRec(arr, key, start, mid - 1);
}

---

💡 3. Binary Search Use Cases

• Search in sorted array

• Find first/last occurrence of an element

• Search in rotated sorted arrays

• Peak elements in mountain arrays

---

✍️ 4. Practice Problems

🔹 Write functions to:

• Find first and last occurrence of an element (e.g. in sorted duplicates)

• Count how many times a number appears in sorted array

• Search in a rotated sorted array

• Find square root using binary search (approximate to floor)

---

🔥 5. BONUS – Search in 2D Matrix

🔹 Use binary search logic on 2D:

public static boolean searchMatrix(int[][] matrix, int target) {
    int rows = matrix.length;
    int cols = matrix[0].length;
    int low = 0, high = rows * cols - 1;

    while (low <= high) {
        int mid = low + (high - low) / 2;
        int value = matrix[mid / cols][mid % cols];

        if (value == target) return true;
        else if (value < target) low = mid + 1;
        else high = mid - 1;
    }
    return false;
}

---

📚 Homework for Day 3:

• Implement both linear and binary search

• Solve 2 problems from LeetCode:

  • Search Insert Position

  • First Bad Version

• Explore: Lower Bound, Upper Bound (optional but forward-thinking)

---

⏭️ What’s Coming on Day 4?

• Sorting Algorithms: Bubble, Selection, Insertion (with time/space analysis)

🧪 Practice Problems Answer Day 2 DSA with C

 

---

✅ 1. Find Maximum and Minimum in an Array

#include <stdio.h>

int main() {
    int n, i;
    int arr[100], max, min;

    printf("Enter number of elements: ");
    scanf("%d", &n);

    printf("Enter %d elements:\n", n);
    for (i = 0; i < n; i++) {
        scanf("%d", &arr[i]);
    }

    max = min = arr[0];

    for (i = 1; i < n; i++) {
        if (arr[i] > max)
            max = arr[i];
        if (arr[i] < min)
            min = arr[i];
    }

    printf("Maximum: %d\n", max);
    printf("Minimum: %d\n", min);

    return 0;
}

---

✅ 2. Count Occurrences of a Given Number

#include <stdio.h>

int main() {
    int n, x, count = 0;
    int arr[100];

    printf("Enter number of elements: ");
    scanf("%d", &n);

    printf("Enter %d elements:\n", n);
    for (int i = 0; i < n; i++) {
        scanf("%d", &arr[i]);
    }

    printf("Enter number to count: ");
    scanf("%d", &x);

    for (int i = 0; i < n; i++) {
        if (arr[i] == x)
            count++;
    }

    printf("Number %d appears %d time(s).\n", x, count);

    return 0;
}

---

✅ 3. Reverse an Array

#include <stdio.h>

int main() {
    int n, arr[100];

    printf("Enter number of elements: ");
    scanf("%d", &n);

    printf("Enter %d elements:\n", n);
    for (int i = 0; i < n; i++) {
        scanf("%d", &arr[i]);
    }

    printf("Reversed array:\n");
    for (int i = n - 1; i >= 0; i--) {
        printf("%d ", arr[i]);
    }

    return 0;
}

---

📘 Homework

---

✅ 4. Copy One Array to Another

#include <stdio.h>

int main() {
    int n, arr1[100], arr2[100];

    printf("Enter number of elements: ");
    scanf("%d", &n);

    printf("Enter %d elements for arr1:\n", n);
    for (int i = 0; i < n; i++) {
        scanf("%d", &arr1[i]);
        arr2[i] = arr1[i];  // Copying
    }

    printf("Copied array (arr2):\n");
    for (int i = 0; i < n; i++) {
        printf("%d ", arr2[i]);
    }

    return 0;
}

---

✅ 5. Merge Two Arrays

#include <stdio.h>

int main() {
    int arr1[50], arr2[50], merged[100];
    int n1, n2, i;

    printf("Enter number of elements in arr1: ");
    scanf("%d", &n1);
    printf("Enter %d elements for arr1:\n", n1);
    for (i = 0; i < n1; i++)
        scanf("%d", &arr1[i]);

    printf("Enter number of elements in arr2: ");
    scanf("%d", &n2);
    printf("Enter %d elements for arr2:\n", n2);
    for (i = 0; i < n2; i++)
        scanf("%d", &arr2[i]);

    for (i = 0; i < n1; i++)
        merged[i] = arr1[i];
    for (i = 0; i < n2; i++)
        merged[n1 + i] = arr2[i];

    printf("Merged array:\n");
    for (i = 0; i < n1 + n2; i++)
        printf("%d ", merged[i]);

    return 0;
}

🚀 DSA with C – Day 2: Arrays & Linear Search

 

🎯 Goal:

• Understand arrays in C.

• Learn how to use loops with arrays.

• Implement Linear Search algorithm.

• Practice multiple array-based programs.

---

🧠 Theory: What is an Array?

• An array is a collection of elements stored in contiguous memory.

• All elements must be of the same type.

• Indexing starts from 0 in C.

🔧 Declaration and Initialization

int arr[5];             // Declaration
int arr[5] = {1, 2, 3, 4, 5};  // Initialization

---

👨‍💻 Basic Program: Input & Output in Arrays

#include <stdio.h>

int main() {
    int arr[5];
    printf("Enter 5 numbers:\n");
    for (int i = 0; i < 5; i++) {
        scanf("%d", &arr[i]);
    }

    printf("You entered:\n");
    for (int i = 0; i < 5; i++) {
        printf("%d ", arr[i]);
    }
    return 0;
}

---

🔍 Linear Search in C

➕ Problem: Given an array and a number x, find if x exists in the array.

✅ Code:

#include <stdio.h>

int main() {
    int arr[100], n, x, found = 0;
    printf("Enter number of elements: ");
    scanf("%d", &n);

    printf("Enter %d elements:\n", n);
    for (int i = 0; i < n; i++)
        scanf("%d", &arr[i]);

    printf("Enter element to search: ");
    scanf("%d", &x);

    for (int i = 0; i < n; i++) {
        if (arr[i] == x) {
            printf("Element found at index %d\n", i);
            found = 1;
            break;
        }
    }

    if (!found)
        printf("Element not found\n");

    return 0;
}

🧠 Time Complexity:

• Best case: O(1)

• Worst case: O(n)

---

🧪 Practice Problems:

1. Find the maximum and minimum element in an array.

2. Count how many times a given number appears in the array.

3. Reverse an array.

---

📘 Homework for Day 2:

• Write a program to copy one array to another.

• Write a program to merge two arrays.

• Try solving one problem from LeetCode Easy using arrays (optional but forward-thinking!).

---

📅 Day 2 Summary

• ✅ Learned arrays

• ✅ Implemented Linear Search

• ✅ Practiced I/O and traversal

---

🧭 Tomorrow: Sorting (Bubble Sort) + Binary Search

Would you like me to create a GitHub repo or planner to track your DSA progress daily?

📝 Day 3 Blog Post: "How to Apply to Universities in Singapore – Step-by-Step Guide for 2025"

 

📝 Day 3 Blog Post: "How to Apply to Universities in Singapore – Step-by-Step Guide for 2025"

🧠 Category: Education > Application & Visa Process

📆 Posting Date: Day 3

🔑 SEO Keywords:

• how to apply to university in Singapore

• Singapore university admission 2025

• study in Singapore for international students

• NUS/NTU application guide

---

✅ Title Tag (SEO):

How to Apply to Universities in Singapore (NUS, NTU, SMU) – 2025 Guide

📌 URL:

/apply-singapore-universities-2025

---

✍️ Introduction:

Singapore is known for its world-class universities, multicultural campus life, and global career opportunities. Whether you're applying to NUS, NTU, SMU, or a polytechnic, this blog will walk you through the step-by-step admission process to study in Singapore in 2025.

---

🧾 Step-by-Step University Application Guide

---

📍 Step 1: Choose Your Institution & Course

Make a shortlist based on:

• Program reputation (e.g., NUS for CS, NTU for Engineering)

• Career goals

• Budget and scholarship availability

🔗 Tip: Visit official sites like www.nus.edu.sg, www.ntu.edu.sg

---

📍 Step 2: Check Eligibility Requirements

Undergraduate:

• GCE A-Levels / IB Diploma / Class 12 Boards (India, Malaysia, etc.)

• English proficiency: IELTS (6.5+) / TOEFL (90+)

Postgraduate:

• Bachelor's degree with GPA ≥ 3.0/4.0

• GRE/GMAT (for MBA, Engineering, etc.)

• Research proposal (if applying for PhD)

✅ Documents you’ll typically need:

• Passport-size photo

• Academic transcripts

• Personal Statement or SOP

• Recommendation letters

• Resume/CV

• Portfolio (for Design/Architecture)

---

📍 Step 3: Submit Online Application

Most applications open between October–April (depending on the university).

University	Application Portal	Typical Deadline
NUS	applications.nus.edu.sg	Jan–Mar 2025
NTU	admissions.ntu.edu.sg	Jan–Mar 2025
SMU	admissions.smu.edu.sg	Mar–May 2025

💡 Tip: Apply early for better chances and scholarship consideration.

---

📍 Step 4: Pay the Application Fee

• Ranges between SGD 20–50

• Use credit/debit card through the application portal

---

📍 Step 5: Attend Interview (if required)

• Some courses (e.g., Medicine, Architecture, MBA) may require:

  • Online interviews

  • Admission tests

  • Portfolio review

---

📍 Step 6: Wait for Offer Letter

If accepted, you’ll receive an IPA (In-Principle Approval) letter, which is required for your Student Pass application.

⏳ Decision Time: Usually 6–10 weeks after application closes.

---

📍 Step 7: Apply for Student Pass via ICA

Use the SOLAR+ system:

1. Your university registers you on SOLAR

2. You receive a unique registration number

3. Log in at ICA SOLAR Portal

4. Submit required documents and pay the fee (~SGD 30–60)

5. Book an appointment for issuance upon arrival

---

🧑‍💻 Optional: Apply for MOE Tuition Grant

If you're not a citizen or PR:

• Apply for the Ministry of Education Tuition Grant

• Sign a bond (work in Singapore for 3 years post-study)

---

📦 Final Checklist Before Moving to Singapore

• Book accommodation

• Buy travel insurance

• Open a local bank account (DBS, OCBC, etc.)

• Register for orientation and course modules

---

❓ FAQs: University Applications in Singapore

Q: Can I apply to multiple universities at once?
✅ Yes, but each has a separate portal and application fee.

Q: Is IELTS mandatory?
✅ Only for students whose previous education was not in English.

Q: What if I miss the application deadline?
✅ Some universities offer rolling admissions or mid-year intakes — check their official calendars.

---

🎓 Conclusion:

Singapore’s education system is competitive but accessible with the right planning. By following this step-by-step guide, you’re already on track to study in one of Asia’s top university destinations.

---

👉 Up Next (Day 4):

"Top Scholarships to Study in Singapore for International Students – 2025 List"

📝 Day 2 Blog Post: "NUS vs NTU: Which University Should You Choose?"

---

✅ Title:

NUS vs NTU: Which Top Singapore University Is Right for You in 2025?

---

✍️ Introduction:

Singapore is home to two world-renowned universities — National University of Singapore (NUS) and Nanyang Technological University (NTU). Both are globally ranked, highly respected, and offer state-of-the-art facilities. So, how do you choose between them?

Let’s break it down and compare NUS and NTU across key factors like ranking, programs, campus life, and career opportunities.

---

🏆 1. Global Rankings

Criteria	NUS	NTU
QS World Ranking 2025	#8 globally	#26 globally
Asia Ranking	#1 in Asia	#5 in Asia

✅ Conclusion: NUS leads globally and regionally, especially in research and science.

---

📚 2. Programs & Strengths

• NUS Strengths: Computer Science, Business, Law, Life Sciences, Medicine.

• NTU Strengths: Engineering, Communication Studies, Education, Environmental Sciences.

✅ Conclusion: NUS is broader with strong interdisciplinary programs. NTU is known for engineering and media.

---

🏫 3. Campus Life & Location

• NUS: Located in Kent Ridge (west), with multiple residential colleges and a city-like vibe.

• NTU: Located in Jurong West, with a green, futuristic campus and eco-friendly architecture.

✅ Conclusion: NTU’s campus is more self-contained and modern. NUS has more urban proximity.

---

👩‍🎓 4. Student Culture

• NUS: Academically rigorous, more research-intensive.

• NTU: Innovation-focused, vibrant student activities and clubs.

✅ Conclusion: NUS leans academic; NTU leans creative and entrepreneurial.

---

💼 5. Graduate Employability

• NUS Graduates: High placement rate, especially in consulting, finance, and tech.

• NTU Graduates: Excellent outcomes in engineering, media, and startups.

✅ Conclusion: Both offer strong employability. NUS edges out slightly for international recognition.

---

💰 6. Tuition & Scholarships

• Tuition fees for most undergraduate courses range from SGD 8,000 – SGD 30,000/year (with MOE Grant).

• Scholarships available at both, including:

  • NUS Global Merit Scholarship

  • NTU Nanyang Scholarship

✅ Conclusion: Similar tuition structures. Both offer generous merit-based support.

---

🧑‍🎓 7. Admission Difficulty

• NUS: Slightly more competitive, especially for Medicine, Law, and CS.

• NTU: Highly competitive too, but more diverse program accessibility.

✅ Conclusion: NUS has stricter entry requirements in top programs.

---

🧾 Final Verdict: NUS or NTU?

You Should Choose...	If You Want...
NUS	Research-heavy environment, broader courses, global recognition
NTU	Tech-forward campus, strong engineering/media focus, innovation

💡 Closing Tip:

Instead of only looking at rankings, explore curriculum fit, campus culture, and career pathways. Visit virtual open houses or connect with current students to help you decide.

---

📢 Up Next (Day 3):

"How to Apply to Universities in Singapore – Step-by-Step Guide for 2025"

📝 Day 1 Blog Post: "Top 10 Courses to Study in Singapore in 2025

 

✍️ Introduction:

Singapore has established itself as one of the top education hubs in Asia, offering globally recognized degrees, cutting-edge facilities, and strong industry ties. Whether you're a local student planning your next step or an international student exploring global opportunities, choosing the right course is crucial.

Here are the top 10 most in-demand and career-focused courses in Singapore for 2025.

---

🎓 1. Computer Science & IT

• Why it’s popular: Singapore is a digital powerhouse, leading Southeast Asia’s tech growth.

• Career Options: Software Engineer, Data Scientist, Cybersecurity Analyst.

• Top Institutions: NUS, NTU, SMU, SIT.

---

⚙️ 2. Engineering

• Specializations: Mechanical, Civil, Electrical, Aerospace.

• Why it’s popular: Infrastructure, sustainability, and smart nation goals.

• Top Institutions: NTU, SUTD, SIT, NUS.

---

🧬 3. Life Sciences & Biotechnology

• Why it’s popular: Backed by Singapore’s biomedical research ecosystem.

• Career Options: Biotech Researcher, Lab Analyst, Environmental Consultant.

• Top Institutions: NUS, Duke-NUS, Yale-NUS.

---

📈 4. Business & Management

• Specializations: Finance, Marketing, International Business, HR.

• Why it’s popular: Singapore is a global financial center.

• Top Institutions: NUS Business School, NTU NBS, SMU, INSEAD.

---

🧑‍🎨 5. Design & Creative Arts

• Specializations: Fashion, Animation, Game Design, Visual Communication.

• Why it’s popular: The media and design sectors are booming with digital demand.

• Top Institutions: LASALLE, NAFA, Raffles Design Institute.

---

🏨 6. Hospitality & Hotel Management

• Why it’s popular: Singapore's vibrant tourism and event economy.

• Career Options: Hotel Manager, Travel Coordinator, F&B Operations.

• Top Institutions: SHATEC, MDIS, EASB.

---

🏥 7. Medicine & Nursing

• Why it’s popular: Aging population and strong healthcare system.

• Career Options: Doctor, Nurse, Pharmacist, Public Health Officer.

• Top Institutions: NUS Yong Loo Lin, Duke-NUS, Parkway College.

---

🏛️ 8. Architecture & Urban Planning

• Why it’s popular: Singapore is a global model for urban sustainability.

• Top Institutions: NUS, SUTD, BCA Academy.

---

✈️ 9. Travel, Aviation & Tourism

• Why it’s popular: Singapore Changi Airport and tourism are world-class.

• Top Institutions: Republic Polytechnic, MDIS, Kaplan.

---

📊 10. Data Science & Artificial Intelligence

• Why it’s popular: AI is driving innovation across all sectors.

• Career Options: Machine Learning Engineer, AI Developer, Data Strategist.

• Top Institutions: NUS, NTU, SMU.

---

💡 Conclusion:

Choosing a course is more than just following trends — it's about aligning your passion with future-ready skills. Singapore’s strong economy and globally ranked institutions make it a top destination for students with big dreams.

Next Up (Day 2): "NUS vs NTU: Which University Should You Choose?"

🚀 DSA with C – Day 1: Introduction & Setup

 

🚀 DSA with C – Day 1: Introduction & Setup

🎯 Goal:

• Understand what DSA is.

• Set up your C environment.

• Write your first C program.

• Learn about time & space complexity (theory).

• Practice basic input/output and loops.

---

🧠 Theory: What is DSA?

• Data Structures = Ways to organize and store data efficiently.

• Algorithms = Step-by-step instructions to solve problems.

• Why DSA matters: Faster apps, better problem-solving, cracking tech interviews.

---

🔧 Setup for C Programming

• Install a C compiler:

  • Windows: Use Code::Blocks or install MinGW and use VS Code.

  • Mac/Linux: Already comes with gcc. Use VS Code or terminal.

• Create your first .c file.

---

👨‍💻 Hello World Program

#include <stdio.h>

int main() {
    printf("Hello, World!\n");
    return 0;
}

Compile using:

gcc hello.c -o hello
./hello

---

📚 Time & Space Complexity (Intro)

• Big O Notation (O(n), O(1), etc.)

• Example:

  • Loop runs n times → O(n)

  • Constant statement → O(1)

Watch a quick 10 min video or read short notes on Big O notation.

---

🧪 Practice: Basic C I/O and Loops

Tasks:

1. Take input of two numbers and print their sum.

2. Print numbers from 1 to n using a for loop.

3. Write a program to find if a number is even or odd.

Example:

#include <stdio.h>

int main() {
    int a, b;
    printf("Enter two numbers: ");
    scanf("%d %d", &a, &b);
    printf("Sum = %d\n", a + b);
    return 0;
}

---

📅 Day 1 Summary

• ✅ Installed C

• ✅ Understood what DSA is

• ✅ Learned about time/space complexity

• ✅ Practiced basic C programs

---

📘 Homework for Day 1:

• Write a program to find the factorial of a number.

• Write a program to print a multiplication table.

---

🌟 Tomorrow: Arrays in C + Linear Search