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First n Prime Numbers

Certification: Basic Level Accuracy: 66.67% Submissions: 3 Points: 10

Write a C++ program to generate and print the first 'n' prime numbers.

Example 1
    

  • Input: n = 5
    • 

  • Output: "2 3 5 7 11"
    • 

  • Explanation: 
      

    • Step 1: Initialize an empty list to store prime numbers.
      • 

    • Step 2: Start checking numbers from 2 (the first prime).
      • 

    • Step 3: For each number, check if it's divisible by any previously found prime up to its square root.
      • 

    • Step 4: If the number isn't divisible by any prime, add it to the prime list.
      • 

    • Step 5: Continue until we have found n prime numbers.
      • 

    • Step 6: Return the list of first n prime numbers: 2, 3, 5, 7, and 11.
      • 

    •
Example 2
    

  • Input: n = 10
    • 

  • Output: "2 3 5 7 11 13 17 19 23 29"
    • 

  • Explanation: 
      

    • Step 1: Initialize an empty list to store prime numbers.
      • 

    • Step 2: Start checking numbers from 2 (the first prime).
      • 

    • Step 3: For each number, check if it's divisible by any previously found prime up to its square root.
      • 

    • Step 4: If the number isn't divisible by any prime, add it to the prime list.
      • 

    • Step 5: Continue until we have found n prime numbers.
      • 

    • Step 6: Return the list of first n prime numbers: 2, 3, 5, 7, 11, 13, 17, 19, 23, and 29.
      • 

    •
Constraints
    

  • 1 ≤ n ≤ 10^4
    • 

  • Output should be space-separated prime numbers
    • 

  • Time Complexity: O(n * sqrt(n))
    • 

  • Space Complexity: O(n)
    •
NumberVariables and Data TypesWiproGoldman Sachs
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Hint
Solution

Solution Hints

    
  
  • Use a helper function to check primality
    • 
  
  • Store primes in a list until reaching count n
    • 
  
  • Optimize divisor checks up to sqrt(num)
    •

Steps to solve by this approach:

 Step 1: Create a vector to store found prime numbers.

 Step 2: Start checking numbers from 2 (the first prime number).

 Step 3: For each number, check if it's divisible by any integer from 2 to its square root.

 Step 4: If no divisors are found, add the number to the prime numbers vector.

 Step 5: Continue until we find the requested number of primes.

 Step 6: Print all the prime numbers found in the vector.

 Step 7: Return from the function.

Submitted Code :