HACKER RANK Project Euler 56 - Powerful Digit Sum - Solution.'Rb'

Project Euler Challenges-56 - Powerful Digit Sum Solution

Problem Statement

This problem is a programming version of Problem 56 from projecteuler.net

A googol (10100) is a massive number: one followed by one-hundred zeros. 100100 is almost unimaginably large: one followed by two-hundred zeros. Despite their size, the sum of the digits in each number is only 1.

Considering natural numbers of the form, ab, where a,b<N, what is the maximum digital sum?

Input Format 
Input contains an integer N

Output Format 
Print the answer corresponding to the test case.

Constraints 
5≤N≤200

Sample Input

5

Sample Output

13

Explanation 
44=256 and 2+5+6=13, which is the maximum digital sum for this range.

Solution:

# Enter your code here. Read input from STDIN. Print output to STDOUT
num=gets
max=0
for i in 1...num.to_i
    for j in 1...num.to_i
        sum=i**j
        #print sum
        #print "\t"
        k=sum
        while k.to_i>0 do
        c=k.to_i%10
        d= d.to_i + c.to_i
        k=k.to_i/10
        end
        #print d.to_i
        #print "\n"
        if d.to_i>max then
            max=d.to_i
            d=0
        end
            d=0
        end
    end
    print max
        

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