Problem 29

问题描述：

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?

 

解决问题：

 

java里有set，每次计算出来，都将值放入其中，然后统计。

 

public static int count(){
		int total = 0;
		Set<Double> all = new HashSet<Double>();
		
		for(int i=DOWN; i<=UP; i++){
			for(int j=DOWN; j<=UP; j++){
				double value = Math.pow(i, j);
				all.add(value);
			}
		}
		
		return all.size();
	}