Issue
Question
A Narcissistic Number is a number which is the sum of its own digits, each raised to the power of the number of digits in a given base. In this Kata, we will restrict ourselves to decimal (base 10).
For example, take 153 (3 digits):
1^3 + 5^3 + 3^3 = 1 + 125 + 27 = 153
and 1634 (4 digits):
1^4 + 6^4 + 3^4 + 4^4 = 1 + 1296 + 81 + 256 = 1634
The Challenge:
Your code must return true or false depending upon whether the given number is a Narcissistic number in base 10.
Error checking for text strings or other invalid inputs is not required, only valid integers will be passed into the function.
My Code
function narcissistic(value) {
let valString = value.toString().split('');
let integerSet = valString.map((item)=>{
return Number(item);
})
let keyFunc = function powerCalc(test){
let a = test[test.length-1];
return test.map((item)=>{
return Math.pow(item, a);
}).reduce((total, item)=>{
return total + item;
}, 0);
}
console.log(keyFunc(153));
if(keyFunc(integerSet)==value){
return true;
}
else {
return false;
}
}
console.log(narcissistic(12432));
console.log(narcissistic(153));The Problem
My console is saying that test.map is not a function.
How can I adjust that function to make it work?
Solution
Two small mistakes:
function narcissistic(value) {
let valString = value.toString().split('');
let integerSet = valString.map((item)=>{
return Number(item);
})
let keyFunc = function powerCalc(test){
let a = test.length; // <------- "raised to the power of the number of digits"
return test.map((item)=>{
return Math.pow(item, a);
}).reduce((total, item)=>{
return total + item;
}, 0);
}
// console.log(keyFunc(153)); // <-- This was throwing an error
if(keyFunc(integerSet)==value){
return true;
}
else {
return false;
}
}
console.log(narcissistic(12432));// false
console.log(narcissistic(153)); // true
console.log(narcissistic(371)); // true
console.log(narcissistic(7)); // trueAnd with a bit of rewriting:
function narcissistic(value) {
const integerSet = value.toString().split('').map(Number);
const pow = integerSet.length;
const sum = integerSet.reduce((total, item) => total + Math.pow(item, pow), 0);
return sum == value;
}
console.log(narcissistic(12432));// false
console.log(narcissistic(153)); // true
console.log(narcissistic(371)); // true
console.log(narcissistic(7)); // trueAnswered By – blex
This Answer collected from stackoverflow, is licensed under cc by-sa 2.5 , cc by-sa 3.0 and cc by-sa 4.0