Project Euler in R Problem 7
Problem 7 of Project Euler asks us to find the 10001^{st} prime number.
The ‘is.prime’ function is the same one that I use in Problem 3. I start the ‘repeat’ loop at 3 so I have to manually set the starting count at 1 (since 2 is prime). I start at 3 because then I can have ‘i’ go up by 2 every iteration (since every prime after 2 is odd). The ‘repeat’ loop then goes through all odd numbers and if they are prime (as determined by the is.prime function I wrote) adds 1 to the count. When the count reaches 10001, the repeat loop breaks and prints the 10001^{st} prime.
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I’ve had this problem done for a few weeks now and I could have sworn that when I ran it back then, the script completed in only a few milliseconds. Now it’s taking about 5 seconds. Not really sure why it’s slower now but I still get the answer pretty quickly.