Friday, June 18, 2021
Home coding Write a program to check whether number is prime or not.

Write a program to check whether number is prime or not.

Given a number and we need to find whether a given number is prime or not.

So what is prime Number?

Prime number is a number that is divisble by itself and 1 .

for example-2,3,5,7,11 …. are prime number because they are divisble by 1 and itself. .

Examples:

input:5
output:true

input:7
output:true

input:10
output:false

#include<iostream>
using namespace std;
int main()
{
 int num;
 cout<<"Enter a number to check Number is prime or not : "<<endl;
 cin>>num;
  bool flag=0;
 for(int i=2;i<=num/2;i++)
 {
  if(num%i==0)//checking whether number have any other divisor
  {
   flag =1;//if divisor present then number is not a prime number
   break;
  }
 }
 if(flag==0)
 {
     cout<<num<<" is a prime number"<<endl;
 }
 else
 {
     cout<<num<<" is not a prime number"<<endl;
 }


}

Output

Enter a number to check Number is prime or not : 5
5 is a prime number

Expected Time Complexity-O(N) where N is the given number.

Expected space Complexity-O(1).

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