6cfd0fc503
* fix: improve Project Euler descriptions and test case Improve formatting of Project Euler test descriptions. Also add poker hands array and new test case for problem 54 * feat: add typeof tests and gave functions proper names for first 100 challenges * fix: continue fixing test descriptions and adding "before test" sections * fix: address review comments * fix: adjust grids in 18 and 67 and fix some text that reference files rather than the given arrays * fix: implement bug fixes and improvements from review * fix: remove console.log statements from seed and solution
1.6 KiB
1.6 KiB
id, challengeType, title, forumTopicId
| id | challengeType | title | forumTopicId |
|---|---|---|---|
| 5900f37d1000cf542c50fe8f | 5 | Problem 16: Power digit sum | 301791 |
Description
215 = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26.
What is the sum of the digits of the number 2exponent?
Instructions
Tests
tests:
- text: <code>powerDigitSum(15)</code> should return a number.
testString: assert(typeof powerDigitSum(15) === 'number');
- text: <code>powerDigitSum(15)</code> should return 26.
testString: assert.strictEqual(powerDigitSum(15), 26);
- text: <code>powerDigitSum(128)</code> should return 166.
testString: assert.strictEqual(powerDigitSum(128), 166);
- text: <code>powerDigitSum(1000)</code> should return 1366.
testString: assert.strictEqual(powerDigitSum(1000), 1366);
Challenge Seed
function powerDigitSum(exponent) {
// Good luck!
return true;
}
powerDigitSum(15);
Solution
function powerDigitSum(exponent) {
const bigNum = [1];
let sum = 0;
for (let i = 1; i <= exponent; i++) {
let count = bigNum.length + 1;
let overflow = 0;
for (let j = 0; j < count; j++) {
let digit = bigNum[j] || 0;
digit = 2 * digit + overflow;
if (digit > 9) {
digit -= 10;
overflow = 1;
} else {
overflow = 0;
}
bigNum[j] = digit;
}
}
bigNum.forEach(function(num) {
return sum += num;
});
return sum;
}