Your task is to construct a building which will be a pile of n cubes. The cube at the bottom will have a volume of n^3, the cube above will have volume of (n-1)^3 and so on until the top which will have a volume of 1^3.
You are given the total volume m of the building. Being given m can you find the number n of cubes you will have to build?
The parameter of the function findNb (find_nb, find-nb, findNb) will be an integer m and you have to return the integer n such as n^3 + (n-1)^3 + ... + 1^3 = m if such a n exists or -1 if there is no such n.
Examples:
findNb(1071225) --> 45
findNb(91716553919377) --> -1
Good Solution1:
public class ASum {
public static long findNb(long m) {
long mm = 0, n = 0;
while (mm < m) mm += ++n * n * n;
return mm == m ? n : -1;
}
}
Good Solution2:
public class ASum {
public static long findNb(long m) {
long total = 0;
int counter = 0;
while (total < m) {
counter++;
total = total + (long) Math.pow(counter, 3);
}
if (m == total)
return counter;
return -1;
}
}
