Find sum of all prime numbers in a given range

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An AI-generated summary of this video lecture.

The video is a programming tutorial from Knowledge Gate, focusing on solving a problem to find the sum of all prime numbers within a given range. The instructor first presents the problem statement, which requires a program to take two integers as input (the start and end of a range) and output the sum of all prime numbers in that range. Two public test cases are shown: for the range 1 to 10, the sum is 17 (2+3+5+7), and for 1 to 100, the sum is 1060. The solution is implemented in C, using a helper function `findPrime` to check if a number is prime by testing divisibility up to its square root. The main function reads the range, iterates through each number, calls `findPrime`, and accumulates the sum of primes. The instructor demonstrates the logic with a step-by-step walkthrough, showing how the sum is calculated for the first few numbers. The video concludes with a live coding session in an online compiler, where the program is executed and the correct output of 17 for the first test case is verified.

Chapters

1. 0:00 – 2:00 00:00-02:00

   The video begins with the 'KNOX MEEHEGATF' logo, which is a stylized version of 'KNOWLEDGE GATE'. It then transitions to a slide that introduces the problem: 'Q6: Write a program to find print sum of all possible prime numbers within the range'. The input is defined as two positive integers separated by a space, representing the start and end of the range. The output is the sum of all prime numbers within that range. Two public test cases are provided: Input: 1 10, Output: 17; and Input: 1 100, Output: 1060. The instructor, Yash Jain Sir, is visible in a small window, and the video is branded as 'PLACEMENT EXPERT' content from 'KNOWLEDGE GATE EDUVENTURES'. The instructor explains the problem and the expected logic.

2. 2:00 – 2:30 02:00-02:30

   The instructor displays the C code for the solution. The code includes a function `int findPrime(int n)` that returns 1 if the number is prime and 0 otherwise. The function uses a flag variable and a loop from 2 to the square root of n to check for divisibility. The `main` function declares variables `n1`, `n2`, `i`, and `sum`, reads the input range, and uses a for loop to iterate from `n1` to `n2`. Inside the loop, it calls `findPrime(i)` and if it returns 1, it adds `i` to the `sum`. Finally, it prints the sum. The instructor explains the logic, and the video shows a live execution in an online compiler where the program is compiled and run, successfully outputting 17 for the test case 1 10.

The video provides a complete, step-by-step guide to solving a common programming interview problem. It starts with a clear problem definition, including input/output specifications and test cases. The solution is then broken down into a modular C program, with a dedicated function to check for primality, which is a fundamental algorithmic concept. The instructor demonstrates the logic of the program by walking through the code and the expected calculations, reinforcing the understanding of the algorithm. The final live coding and execution in an online compiler serve as a practical validation of the solution, ensuring the code is correct and functional.