Write a Program to check whether the given number N is prime or not.
For a given number N check if it is prime or not. A prime number is a number that is only divisible by 1 and itself.
The only line of input contains a single integer N.
The only line of the output prints either true or false.
0 <= N <= 10,000
5
true
10
false
10 has 2 factors 2, 5.
In the program, a for loop is iterated from i = 2 to i < n.
In each iteration, whether n is perfectly divisible by i is checked using:
if (n % i == 0)
If n is perfectly divisible by I, n is not a prime number. In this case, the flag is set to False.
After the loop, if n is a prime number, the flag will still be True. However, if n is a non-prime number, the flag will be False.
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Interview problems
easy cpp
#include <bits/stdc++.h>
using namespace std;
int sqrt(int N) {
int low = 1, high = N/2;
while (low <= high) {
long long mid = low + (high - low) / 2;
if (mid * mid == N) return mid;
else if (mid * mid < N) low = mid + 1;
else high = mid - 1;
}
return low;
}
int main() {
int n;
cin>>n;
if(n<=1) cout<< "false";
else{
int flag = 0;
int val = sqrt(n);
for(int i=2;i<=val;i++){
if (n % i == 0) {
cout << "false";
flag = 1;
break;
}
}
if (!flag)
cout << "true";
}
return 0;
}
Interview problems
Easy Java solution
public static boolean isPrime(int n) {
if(n==1){
return false;
}
for(int i=2;i<=Math.sqrt(n);i++){
if(n%i==0 || n%(i+2)==0){
return false;
}
}
return true;
}
Interview problems
Java code
import java.util.* ;
import java.io.*;
class Solution {
static boolean isPrime(int n){
if(n==1){
return false;
}
if(n==2||n==3){
return true;
}
if(n%2==0||n%3==0){
return false;
}
for(int i=5;i<=Math.sqrt(n);i=i+6){
if(n%i==0 || n%(i+2)==0){
return false;
}
}
return true;
}
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
System.out.println(isPrime(n));
}
}
Interview problems
Optimal solution solve all test cases
#include <iostream>
using namespace std;
int main() {
int n;
cin >> n;
if (n <= 1) {
cout << "false";
return 0;
}
bool isPrime = true;
for (int i = 2; i * i <= n; i++) {
if (n % i == 0) {
isPrime = false;
break;
}
}
if (isPrime) {
cout << "true";
} else {
cout << "false";
}
return 0;
}
Interview problems
Easy Java Solution
import java.util.Scanner;
class Solution {
static boolean isPrime(int n){
if(n==1){
return false;
}
if(n==2||n==3){
return true;
}
if(n%2==0||n%3==0){
return false;
}
for(int i=5;i<=Math.sqrt(n);i=i+6){
if(n%i==0 || n%(i+2)==0){
return false;
}
}
return true;
}
public static void main(String args[]) {
// Write code here
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
System.out.println(isPrime(n));
}
}
Java Solution
import java.util.* ;
import java.io.*;
class Solution {
public static void main(String args[]) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
int i=1;
int temp=0;
while(i<=n){
if(n%i==0)
temp++;
i++;
}
if(temp==2){
System.out.println("true");
}
else{
System.out.println("false");
}
}
}
Interview problems
C++ SOLUTION - BEST AND OPTIMAL
#include <bits/stdc++.h>
#include <iostream>
using namespace std;
bool isprime(int n) {
if (n <2) {
return false;
}
for (int i = 2; i <= sqrt(n); i++) {
if (n % i == 0) {
return false;
}
}
return true;
}
int main() {
long int n;
cin >> n;
if (isprime(n)) {
cout << "true";
} else {
cout << "false";
}
return 0;
}
Interview problems
check prime or not [cpp]
#include <bits/stdc++.h>
using namespace std;
bool isPrime(int n){
if(n<=1) return false;
for(int i=2; i<=n/2; i++){
if(n%i==0) return false;
}
return true;
}
int main() {
int n;
cin>>n;
if(isPrime(n)) cout<<"true";
else cout<<"false";
return 0;
}
Interview problems
Easy cpp code solution
#include <bits/stdc++.h>
#include <iostream>
using namespace std;
int main() {
//Write your code here
int n;
cin>>n;
int flag=0;
vector<bool> prime(n+1, true);
prime[0]=prime[1]=false;
for(int i=2; i< n+1; i++){
if(prime[i]){
if(n==i){
cout<<"true";
flag=1;
break;
}
for(int j=2*i; j<n+1;j=j+i){
prime[j]=false;
}
}
}
if(flag==0){
cout<<"false";
}
}
Interview problems
Basic Approach by user defined function
#include <bits/stdc++.h>
using namespace std;
bool isPrime(int n)
{
// Corner case
if (n <= 1)
return false;
// Check from 2 to n-1
for (int i = 2; i < n; i++)
if (n % i == 0)
return false;
return true;
}
