The Cantor expansion of the natural number x is x = ak * k!+a(k − 1) *(k − 1)!+.... + a2 * 2!+a1*1! where all the ai (digits) satisfy 0 ≤ ai ≤ i it is easy to find a algorithm,we find the largest integer k that can satisfy 给一个正整数求出它的康