freeCodeCamp/curriculum/challenges/english/08-coding-interview-prep/project-euler/problem-48-self-powers.english.md

id	challengeType	title
5900f39c1000cf542c50feaf	5	Problem 48: Self powers

Description

The series, 1¹ + 2² + 3³ + ... + 10¹⁰ = 10405071317. Find the last ten digits of the series, 1¹ + 2² + 3³ + ... + 1000¹⁰⁰⁰.

Instructions

Tests

tests:
  - text: <code>selfPowers(10, 3)</code> should return 317.
    testString: assert.strictEqual(selfPowers(10, 3), 317, '<code>selfPowers(10, 3)</code> should return 317.');
  - text: <code>selfPowers(150, 6)</code> should return 29045.
    testString: assert.strictEqual(selfPowers(150, 6), 29045, '<code>selfPowers(150, 6)</code> should return 29045.');
  - text: <code>selfPowers(673, 7)</code> should return 2473989.
    testString: assert.strictEqual(selfPowers(673, 7), 2473989, '<code>selfPowers(673, 7)</code> should return 2473989.');
  - text: <code>selfPowers(1000, 10)</code> should return 9110846700.
    testString: assert.strictEqual(selfPowers(1000, 10), 9110846700, '<code>selfPowers(1000, 10)</code> should return 9110846700.');

Challenge Seed

function selfPowers(power, lastDigits) {
  // Good luck!
  return true;
}

selfPowers(1000, 10);

Solution

function selfPowers(power, lastDigits) {
  let sum = 0;
  const modulo = Math.pow(10, lastDigits);

  for (let i = 1; i <= power; i++) {
    let temp = i;
    for (let j = 1; j < i; j++) {
      temp *= i;
      temp %= modulo;
    }

    sum += temp;
    sum %= modulo;
  }

  return sum;
}