Tags: gmpy python
Rating:
## It's Prime Time! (PPC, 60p)
Description: We all know that prime numbers are quite important in cryptography. Can you help me to find some?
###ENG
[PL](#pl-version)
The server sends input as:
Hi, you know that prime numbers are important, don't you? Help me calculating the next prime!
Level 1.: Find the next prime number after 8:
And our task is to provide next prime numer after given number.
Numbers were small so we could have implemented a naive algorithm or a sieve, but instead we just used `gmpy2.next_prime`:
```python
import re
import socket
import gmpy2
from time import sleep
def main():
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(("188.166.133.53", 11059))
regex = "Level \d+\.: .* (\d+)"
initial_data = str(s.recv(4096))
print(initial_data)
while True:
sleep(1)
task = str(s.recv(4096))
m = re.search(regex, task)
print(task)
previous_number = int(m.group(1))
result = int(gmpy2.next_prime(previous_number))
print("result = "+str(result))
s.sendall(str(result) + "\n")
pass
main()
```
And after 100 examples we got a flag: `IW{Pr1m3s_4r3_!mp0rt4nt}`
###PL version
Serwer przysyła dane w formacie:
Hi, you know that prime numbers are important, don't you? Help me calculating the next prime!
Level 1.: Find the next prime number after 8:
A naszym zadaniem jest zwrócić kolejną liczbę pierwszą po podnanej liczbie.
Liczby były bardzo małe więc mogliśmy użyć algorytmu naiwnego albo sita, ale zamiast tego użyliśmy gotowego `gmpy2.next_prime`:
```python
import re
import socket
import gmpy2
from time import sleep
def main():
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(("188.166.133.53", 11059))
regex = "Level \d+\.: .* (\d+)"
initial_data = str(s.recv(4096))
print(initial_data)
while True:
sleep(1)
task = str(s.recv(4096))
m = re.search(regex, task)
print(task)
previous_number = int(m.group(1))
result = int(gmpy2.next_prime(previous_number))
print("result = "+str(result))
s.sendall(str(result) + "\n")
pass
main()
```
I po 100 przykładach dostaliśmy flagę: `IW{Pr1m3s_4r3_!mp0rt4nt}`
