原题链接 http://projecteuler.net/problem=29

Distinct powers

Consider all integer combinations of a^b for 2 <= a <= 5 and 2 <= b <= 5:

2²=4, 2³=8, 2⁴=16, 2⁵=32
3²=9, 3³=27, 3⁴=81, 3⁵=243
4²=16, 4³=64, 4⁴=256, 4⁵=1024
5²=25, 5³=125, 5⁴=625, 5⁵=3125

If they are then placed in numerical order, with any repeats removed, we get the following sequence of 15 distinct terms:

4, 8, 9, 16, 25, 27, 32, 64, 81, 125, 243, 256, 625, 1024, 3125

How many distinct terms are in the sequence generated by a^b for 2 <= a <= 100 and 2 <= b <= 100?

唯一的幂方

考虑a^b形式的所有整数，其中2 <= a <= 5,2 <= b <= 5:

2²=4, 2³=8, 2⁴=16, 2⁵=32
3²=9, 3³=27, 3⁴=81, 3⁵=243
4²=16, 4³=64, 4⁴=256, 4⁵=1024
5²=25, 5³=125, 5⁴=625, 5⁵=3125

如果将它们按大小排序，去除重复数字，我们可以得到如下15个唯一的数：

4, 8, 9, 16, 25, 27, 32, 64, 81, 125, 243, 256, 625, 1024, 3125

求在a^b 其中 2 <= a <= 100 ，2 <= b <= 100中，唯一的数有多少个？

解法：

这里用一个set来存。数学方法还没想到。