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57 changes: 57 additions & 0 deletions src/main/java/com/thealgorithms/maths/GoldbachConjecture.java
Original file line number Diff line number Diff line change
@@ -0,0 +1,57 @@
package com.thealgorithms.maths;

import java.util.Scanner;

import static java.lang.String.format;

/**
* This is a representation of the unsolved problem of Goldbach's Projection, according to which every
* even natural number greater than 2 can be written as the sum of 2 prime numbers
* More info: https://en.wikipedia.org/wiki/Goldbach%27s_conjecture
* @author Vasilis Sarantidis (https://github.com/BILLSARAN)
*/

public final class GoldbachConjecture {
private GoldbachConjecture(){
}

/**
* Checks whether a number is prime or not
* @param n the input number
* @return true if n is prime, else return false
*/
private static boolean isPrime(int n){
int i;
if(n <= 1 || (n%2 == 0 && n!=2)){
return false;
}
else {
for(i = 3; i<Math.sqrt(n); i+=2){
if(n%i == 0)
return false;
}
}
return true;
}

public static void main(String[] args){

Scanner scanner = new Scanner(System.in);
System.out.println("Enter a number");
int n = scanner.nextInt();
int flag = 0;

if(n%2 == 0 && n>2) {
for(int i=0;i<=n/2 && flag==0;i++)
if(isPrime(i))
if(isPrime(n-i))
{
System.out.println(format("%d+%d=%d", i, n-i, n));
flag=1;
}
}
else
System.out.println("Wrong Input");
}

}
Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@

import static org.junit.jupiter.api.Assertions.assertEquals;

import com.thealgorithms.bitmanipulation.FindNthBit;
import org.junit.jupiter.api.Test;

public class FibonacciSeriesTest {
Expand All @@ -23,5 +24,9 @@ public void testFibonacci() {
assertEquals(144, FibonacciSeries.fibonacci(12));
assertEquals(233, FibonacciSeries.fibonacci(13));
assertEquals(377, FibonacciSeries.fibonacci(14));
assertEquals(610, FibonacciSeries.fibonacci(15));
assertEquals(6765, FibonacciSeries.fibonacci(20));
assertEquals(75025, FibonacciSeries.fibonacci(25));
assertEquals(832040, FibonacciSeries.fibonacci(30));
}
}
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