水仙花数：N位整数，它等于各位上的数字的N次方之和，例如有一个N位数字，a1a2a3a4.....aN = a1^N +a2^N+......aN^N

算法原理： 注意：以下 sum 为各位上的数字的N次方之和 sum_a为集合a中的数的sum-Daffodils number: N-bit integer, which is equal to you the numbers on the N-th power of, for example, an N-bit digital, a1a2a3a4 ..... an = a1 ^ N+a2 ^ N+ ...... AN N algorithm: Note: The following sum set a number for you on N-th power of digital sum_a sum