Problem 29 Distinct powers (set)

Distinct powers

Problem 29

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?

Answer:

9183Completed on Sat, 29 Oct 2016, 02:28

题解;把结果扔进set里面就可以了，要用到double类型，双精度型占8 个字节（64位）内存空间，其数值范围为1.7E-308～1.7E+308。10^100只有201位，可以用double类型，再大的话，就long double....

long double范围为-1.2*10^-4932~1.2*10^4932....

代码：

#include<bits/stdc++.h>using namespace std;/*long long q_mod(int a,int b){long long ans=1;while(b>0){if(b&1)ans=(ans*a);b>>=1;a=(a*a);}return ans;}*/int main(){set<double> s;for(double i=2;i<=100;i++){for(double j=2;j<=100;j++){s.insert(pow(i,j));}}cout<<s.size()<<endl;return 0;}