Project Euler Problem 4:Largest palindrome product

A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.

Find the largest palindrome made from the product of two 3-digit numbers.

Solution:-

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

public class Problem_4{ public static void main(String []args){ int pal=0; int fdigit=0; int sdigit=0; for(int i=100;i<999;i++){ for(int j=100;j<999;j++){ int temp= i*j; if(isPalindrome(temp)){ if(temp>pal){ pal=temp; fdigit=i; sdigit=j; } } } } System.out.println("Largest palindrome is "+pal+"\n First Digit is"+fdigit+"\n Second Digit is"+sdigit); } static boolean isPalindrome(int a){ int rev=0; int temp=a; while(temp>0){ rev=temp%10 + rev*10; temp=temp/10; } if(rev==a) return true; else return false; } }

Project Problem 3: Largest prime factor

The prime factors of 13195 are 5, 7, 13 and 29.

What is the largest prime factor of the number 600851475143 ?

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Solution:

public class Problem_3{
    
    public static void main(String[] args){
        
        long a=600851475143l;
        long prime=0;
        
        for(long i=1l;i<a;a++){
            long temp=0l;
            if(a%i==0){
                if(isPrime(i)){
                    System.out.println("Prime factor is "+i);
                }
            }
        }
    }
    
    static boolean isPrime(long a){
        for(long i=2l;i<a;i++){
            if(a%i==0)
                return false;
        }
        
        return true;
    }
    
}

Project Euler Problem 2: Even Fibonacci numbers

Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be:

1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...

By considering the terms in the Fibonacci sequence whose values do not exceed four million, find the sum of the even-valued terms.

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Solution:-

public class Problem_2{

    public static void main(String[] args){
        
        int prev =1;
        int result=0;
        double sum=0;
        
        while(i<4000000){
            result=i+prev;
            prev=i;
            i=result;
            
            if(result(%2==0){
                sum=sum+result;
                System.out.print(","+i);
            }
        }
        
        System.out.println("\nSum is "+sum);
    }
}