We use cookies to ensure you have the best browsing experience on our website. Please read our cookie policy for more information about how we use cookies.
This was kinda hard man jesus. The key insight: simplify x, factoring out every 5 and 2 from it. You have to find the smallest a such that 444... (of length a) is divided by the simplified x - you can do all these computations modulo simplified x, i.e. start at 0, multiply-by-10-then-add-4, reduce modulo simplified x until you get 0, the amt of iterations this took is the value of a. using the 2's and 5's you factored at the start (+the knowledge that the 4... number has no 5 factors and 2 2 factors) you can figure out the amt of 0s you need. Repeat this for some other values of a (up to a+b for the first pair you find) to ensure you find the one w the smallest (a+b, a) lexicographically and that's the solution.
Cookie support is required to access HackerRank
Seems like cookies are disabled on this browser, please enable them to open this website
Easy math
You are viewing a single comment's thread. Return to all comments →
This was kinda hard man jesus. The key insight: simplify x, factoring out every 5 and 2 from it. You have to find the smallest a such that 444... (of length a) is divided by the simplified x - you can do all these computations modulo simplified x, i.e. start at 0, multiply-by-10-then-add-4, reduce modulo simplified x until you get 0, the amt of iterations this took is the value of a. using the 2's and 5's you factored at the start (+the knowledge that the 4... number has no 5 factors and 2 2 factors) you can figure out the amt of 0s you need. Repeat this for some other values of a (up to a+b for the first pair you find) to ensure you find the one w the smallest (a+b, a) lexicographically and that's the solution.