830. Prime numbers

Print all prime numbers in the range from m to n, inclusive.

Input. Two positive integers m and n (2 ≤ m ≤ n ≤ 300000).

Output. Print all prime numbers in the range [m; n] in ascending order, one number per line. If there are no prime numbers in the range from m to n, print “Absent”.

Sample input 1	Sample output 1
2 5	2 3 5

Sample input 2	Sample output 2
4 4	Absent

РЕШЕНИЕ

prime test

Algorithm analysis

Iterate through all positive integers in the range from m to n and print only the prime numbers. If there are no prime numbers in the range [m; n], print the message “Absent.”

Algorithm implementation

The function IsPrime checks whether the number n is prime.

· If n is prime, the function returns 1.

· Otherwise, the function returns 0.

int IsPrime(int n)

{

for(int i = 2; i <= sqrt(n); i++)

if (n % i == 0) return 0;

return 1;

}

The main part of the program. Read the input data.

scanf("%d %d",&m,&n);

Initially, assume that there are no prime numbers in the range. Set flag = 0.

flag = 0;

Iterate through the numbers from m to n. If the current number is prime, print it and set flag = 1.

for(i = m; i <= n; i++)

{

if (IsPrime(i))

{

printf("%d\n",i);

flag = 1;

}

If no prime number is printed (flag = 0), print the message “Absent”.

if (flag == 0) puts("Absent");

Python implementation

import math

The function IsPrime checks whether the number n is prime.

· If n is prime, the function returns 1.

· Otherwise, the function returns 0.

def IsPrime(n):

for i in range(2, int(math.sqrt(n)) + 1):

if n % i == 0: return False

return True

The main part of the program. Read the input data.

m, n = map(int,input().split())

Initially, assume that there are no prime numbers in the range. Set flag = 0.

flag = 0

Iterate through the numbers from m to n. If the current number is prime, print it and set flag = 1.