ProjectEuler.net Solution In Javascript

_Project Euler Solution.md

ProjectEuler.net Solution In Javascript

project_1.js

// Title : Multiples of 3 and 5
// Task : 
//  If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23. 
//  Find the sum of all the multiples of 3 or 5 below 1000.

let sum_of_all = 0;

for (i = 0; i < 1000; i++)
    if (i % 3 == 0 || i % 5 == 0) sum_of_all += i;

console.log(sum_of_all);
// 233168

project_2.js

// Titlw : Even Fibonacci Number
// Task : 
//  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.

let [x, y, z] = [0, 1, 0];
let result = 0;

while (y < 4000000) {
    z = x + y;
    [x, y] = [y, z];

    if (y % 2 == 0) result += y;
}

console.log(result);
// 4613732

project_3.js

// Title : Largest Prime Factor
// Task : 
//  The prime factors of 13195 are 5, 7, 13 and 29.
//  What is the largest prime factor of the number 600851475143 ?

let number = 600851475143;
let primes = [];

for (let i = 2; i <= number; i++) {
    if (number % i === 0) {
        if (!primes.length) primes.push(i);
        else {
            let is_add = true;
            primes.forEach((value) => {
                if (i % value === 0) is_add = false;
            });
            if (is_add) primes.push(i);
        }
        number /= i;
    }
}

console.log(primes[primes.length - 1]);

project_4.js

// Title : Largest Palindrome Product
// Task :
//  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.

let final_result = 0;

const floor = (number) => {
    return number - ( number % 1);
};

for(let i = 111; i <= 999; i++){
    for (let j = 111; j <= 999; j++) {
        let result = String(i * j);
        let reverse_result = result.split("").reverse().join("");

        if(result == reverse_result){
            result = i * j;
            
            if (final_result < i * j){
                final_result = i * j;
            }
        }
    }
}

console.log(final_result)

project_5.js

// Title : Smallest Multiple
// Task : 
//     2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder.
//     What is the smallest positive number that is evenly divisible by all of the numbers from 1 to 20 ?

let result, number = 0,
process = true,
divisible = Array(20).fill(1).map( (v,i) => v+i);

while(process){
    number ++;
    let is_continue = false;
    divisible.forEach( v => {
        if(number % v !== 0) is_continue = true;
    });

    if(is_continue){
        continue;
    }

    result = number;
    process = false;
}

console.log(result);
// 232792560

project_6.js

// Title: Sum square difference
// Task:
//     <p>The sum of the squares of the first ten natural numbers is,</p>
//     $$1^2 + 2^2 + ... + 10^2 = 385$$
//     <p>The square of the sum of the first ten natural numbers is,</p>
//     $$(1 + 2 + ... + 10)^2 = 55^2 = 3025$$
//     <p>Hence the difference between the sum of the squares of the first ten natural numbers and the square of the sum is $3025 - 385 = 2640$.</p>
//     <p>Find the difference between the sum of the squares of the first one hundred natural numbers and the square of the sum.</p>

const sum = (num, q=1) => {
    return (num == 0) ? 0 : (num ** q) + sum(num-1,q);
}

let first_number = sum(100) ** 2;
let second_number = sum(100,2);
console.log(first_number - second_number);