14(June) Armstrong Numbers

14. Armstrong Numbers

The problem can be found at the following link: Question Link

Problem Description

You are given a 3-digit number n. Determine whether it is an Armstrong number or not.

An Armstrong number of three digits is a number such that the sum of the cubes of its digits is equal to the number itself. For example, 371 is an Armstrong number since (3^3 + 7^3 + 1^3 = 371).

Example:

Input:

n = 153

Output:

Yes

Explanation: 153 is an Armstrong number since (1^3 + 5^3 + 3^3 = 153). Hence, the answer is "Yes".

My Approach

1. Initialization:

   • Convert the number to a string to easily access each digit.

2. Sum Calculation:

   • Calculate the sum of the cubes of each digit.

3. Comparison:

   • Compare the calculated sum with the original number.

   • If they are equal, return "Yes".

   • Otherwise, return "No".

Time and Auxiliary Space Complexity

• Expected Time Complexity: O(1), as we perform a constant number of operations regardless of the size of the input.

• Expected Auxiliary Space Complexity: O(1), as we only use a constant amount of additional space.

Code

C++

class Solution {
public:
    string armstrongNumber(int n) {
        string ans = to_string(n);
        if ((pow((ans[0]-'0'), 3) + pow((ans[1]-'0'), 3) + pow((ans[2]-'0'), 3)) == n) {
            return "true";
        }
        return "false";
    }
};

Java

class Solution {
    static String armstrongNumber(int n) {
        int original = n;
        int sum = 0;
        while (n > 0) {
            int digit = n % 10;
            sum += Math.pow(digit, 3);
            n /= 10;
        }
        return sum == original ? "true" : "false";
    }
}

Python

class Solution:
    def armstrongNumber(self, n):
        original = n
        sum = 0
        while n > 0:
            digit = n % 10
            sum += digit ** 3
            n //= 10
        return "true" if sum == original else "false"

Contribution and Support

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