javascript armstrong number 测试用例错误

Question

我要解决的问题是:

Write a javascript program which returns true when a given number is Armstrong number and false otherwise. Any n digit number is armstrong number if sum of nth power of each digit equals to the number itself. Example: 153 is a 3 digit armstrong number because sum of 3rd power of each digit equals to 153 (153 = 1*1*1 + 5*5*5 + 3*3*3).

Hint: Use Math.pow(i,n) to calculate nth power of i. Use parseInt(i) to get integer value of i. Your output code should be in the format console.log("Result is ", variableName)

我的代码是:

var num = prompt("Enter a number to check Armstrong");
var t = "Armstrong";
var f = "Not Armstrong";

function armst(x) {
    var a = x, b, sum = 0;
    while (a > 0) {
        b = a % 10;
        sum += (b * b * b);
        a = parseInt(a / 10);
    }

    if (sum === x) {
        return t;
    } else {
        return f;
    }
}

var output = armst(num);
console.log("Result is : ", output);

当我在类(class)网站上运行这段代码时，它给出了正确的输出，但没有通过编译器的所有测试用例。

我错过了什么吗？哪些地方可以改进？

Answer 1

为了获得 narcissistic number/Armstrong number，需要将数字的长度作为字符串作为n取幂求和。

只是个人的话，因为规范，我会采取Math.floor ，因为您已经有了一个数字，而不是 parseInt .

function armst(x) {
    var value = parseInt(x, 10),
        rest = value,
        digit,
        sum = 0,
        n = x.toString().length;       // add toString, if a number is entered

    while (rest) {
        digit = rest % 10;
        rest = Math.floor(rest / 10);
        sum += Math.pow(digit, n);    // use it here
    }

    return sum === value
        ? "Armstrong"
        : "Not Armstrong";
}


var num = prompt("Enter a number to check Armstrong"), // try with 54748
    output = armst(num);

console.log("Result is: ", output);