【POJ 2409】 Let it Bead（Polya）

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【POJ 2409】 Let it Bead（Polya）

Description

Input

Output

For each test case output on a single line the number of unique bracelets. The figure below shows the 8 different bracelets that can be made with 2 colors and 5 beads.

Sample Input

1 1
2 1
2 2
5 1
2 5
2 6
6 2
0 0

Sample Output

1
2
3
5
8
13
21

Source

裸Polya。，经过旋转对称后一样的算一种。

这样公式套上。。。。

#include <iostream>
#include <cmath>
#include <vector>
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <queue>
#include <stack>
#include <list>
#include <algorithm>
#include <map>
#include <set>
#define LL long long
#define Pr pair<int,int>
#define fread() freopen("in.in","r",stdin)
#define fwrite() freopen("out.out","w",stdout)

using namespace std;
const int INF = 0x3f3f3f3f;
const int msz = 10000;
const int mod = 1e9+7;
const double eps = 1e-8;


int main()
{
	//fread();
	//fwrite();

	int c,s;
	int ans;
	while(~scanf("%d%d",&c,&s) && (c+s))
	{
		ans = 0;
		for(int i = 1; i <= s; ++i)
			ans += (int)pow(1.0*c,__gcd(i,s));

		if(s&1) printf("%d\n",(ans+(int)pow(1.0*c,(s+1)/2)*s)/(2*s));
		else printf("%d\n",(ans+(int)pow(1.0*c,s/2)*(s/2)+(int)pow(1.0*c,(s-2)/2+2)*(s/2))/(2*s));
	}

	return 0;
}

【POJ 2409】 Let it Bead（Polya）

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原文地址：http://blog.csdn.net/challengerrumble/article/details/51439560