4fd800b3a8 2011-02-23        kinaba: #include <iostream>
4fd800b3a8 2011-02-23        kinaba: #include <sstream>
4fd800b3a8 2011-02-23        kinaba: #include <iomanip>
4fd800b3a8 2011-02-23        kinaba: #include <vector>
4fd800b3a8 2011-02-23        kinaba: #include <string>
4fd800b3a8 2011-02-23        kinaba: #include <map>
4fd800b3a8 2011-02-23        kinaba: #include <set>
4fd800b3a8 2011-02-23        kinaba: #include <algorithm>
4fd800b3a8 2011-02-23        kinaba: #include <numeric>
4fd800b3a8 2011-02-23        kinaba: #include <iterator>
4fd800b3a8 2011-02-23        kinaba: #include <functional>
4fd800b3a8 2011-02-23        kinaba: #include <complex>
4fd800b3a8 2011-02-23        kinaba: #include <queue>
4fd800b3a8 2011-02-23        kinaba: #include <stack>
4fd800b3a8 2011-02-23        kinaba: #include <cmath>
4fd800b3a8 2011-02-23        kinaba: #include <cassert>
4fd800b3a8 2011-02-23        kinaba: #include <cstring>
4fd800b3a8 2011-02-23        kinaba: using namespace std;
4fd800b3a8 2011-02-23        kinaba: typedef long long LL;
4fd800b3a8 2011-02-23        kinaba: typedef complex<double> CMP;
4fd800b3a8 2011-02-23        kinaba: 
4fd800b3a8 2011-02-23        kinaba: int bitcnt(int m)
4fd800b3a8 2011-02-23        kinaba: {
4fd800b3a8 2011-02-23        kinaba: 	int c = 0;
4fd800b3a8 2011-02-23        kinaba: 	for(;m;m>>=1)
4fd800b3a8 2011-02-23        kinaba: 		c += (m&1);
4fd800b3a8 2011-02-23        kinaba: 	return c;
4fd800b3a8 2011-02-23        kinaba: }
4fd800b3a8 2011-02-23        kinaba: 
4fd800b3a8 2011-02-23        kinaba: class RabbitStepping { public:
4fd800b3a8 2011-02-23        kinaba: 	double getExpected(string field, int r)
4fd800b3a8 2011-02-23        kinaba: 	{
4fd800b3a8 2011-02-23        kinaba: 		cerr<<field.size()<<endl;
4fd800b3a8 2011-02-23        kinaba: 		int ex = 0;
4fd800b3a8 2011-02-23        kinaba: 		int cn = 0;
4fd800b3a8 2011-02-23        kinaba: 
4fd800b3a8 2011-02-23        kinaba: 		int N = field.size();
4fd800b3a8 2011-02-23        kinaba: 		for(int mask=1; mask<(1<<N); ++mask)
4fd800b3a8 2011-02-23        kinaba: 			if( bitcnt(mask) == r )
4fd800b3a8 2011-02-23        kinaba: 			{
4fd800b3a8 2011-02-23        kinaba: 				vector< pair<int,int> > rs;
4fd800b3a8 2011-02-23        kinaba: 				for(int i=0; i<N; ++i)
4fd800b3a8 2011-02-23        kinaba: 					if( mask & (1<<i) )
4fd800b3a8 2011-02-23        kinaba: 						rs.push_back(make_pair(-1,i));
4fd800b3a8 2011-02-23        kinaba: 				int left = run(field, rs, N);
4fd800b3a8 2011-02-23        kinaba: 				ex += left;
4fd800b3a8 2011-02-23        kinaba: 				cn += 1;
4fd800b3a8 2011-02-23        kinaba: 			}
4fd800b3a8 2011-02-23        kinaba: 		return double(ex) / cn;
4fd800b3a8 2011-02-23        kinaba: 	}
4fd800b3a8 2011-02-23        kinaba: 
4fd800b3a8 2011-02-23        kinaba: 	int run(const string& field, vector< pair<int,int> >& rs, int size)
4fd800b3a8 2011-02-23        kinaba: 	{
4fd800b3a8 2011-02-23        kinaba: 		while( size > 2 && !rs.empty() )
4fd800b3a8 2011-02-23        kinaba: 		{
4fd800b3a8 2011-02-23        kinaba: 			oneStep(field, rs, size);
4fd800b3a8 2011-02-23        kinaba: 			int cnt[20] = {};
4fd800b3a8 2011-02-23        kinaba: 			for(int i=0; i<rs.size(); ++i)
4fd800b3a8 2011-02-23        kinaba: 				cnt[rs[i].second] ++;
4fd800b3a8 2011-02-23        kinaba: 			vector< pair<int,int> > rs2;
4fd800b3a8 2011-02-23        kinaba: 			for(int i=0; i<rs.size(); ++i)
4fd800b3a8 2011-02-23        kinaba: 				if( cnt[rs[i].second] == 1 )
4fd800b3a8 2011-02-23        kinaba: 					rs2.push_back(rs[i]);
4fd800b3a8 2011-02-23        kinaba: 			rs.swap(rs2);
4fd800b3a8 2011-02-23        kinaba: 		}
4fd800b3a8 2011-02-23        kinaba: 		return rs.size();
4fd800b3a8 2011-02-23        kinaba: 	}
4fd800b3a8 2011-02-23        kinaba: 
4fd800b3a8 2011-02-23        kinaba: 	void oneStep(const string& field, vector< pair<int,int> >& rs, int& size)
4fd800b3a8 2011-02-23        kinaba: 	{
4fd800b3a8 2011-02-23        kinaba: 		for(int i=0; i<rs.size(); ++i) {
4fd800b3a8 2011-02-23        kinaba: 			int prev = rs[i].first;
4fd800b3a8 2011-02-23        kinaba: 			int& cur = rs[i].second;
4fd800b3a8 2011-02-23        kinaba: 			rs[i].first = cur;
4fd800b3a8 2011-02-23        kinaba: 			if( cur == 0 )
4fd800b3a8 2011-02-23        kinaba: 				cur ++;
4fd800b3a8 2011-02-23        kinaba: 			else if( cur >= size-2 )
4fd800b3a8 2011-02-23        kinaba: 				cur --;
4fd800b3a8 2011-02-23        kinaba: 			else if( field[cur]=='W' )
4fd800b3a8 2011-02-23        kinaba: 				cur --;
4fd800b3a8 2011-02-23        kinaba: 			else if( field[cur]=='B' )
4fd800b3a8 2011-02-23        kinaba: 				cur ++;
4fd800b3a8 2011-02-23        kinaba: 			else if( prev == -1 )
4fd800b3a8 2011-02-23        kinaba: 				cur --;
4fd800b3a8 2011-02-23        kinaba: 			else
4fd800b3a8 2011-02-23        kinaba: 				cur = prev;
4fd800b3a8 2011-02-23        kinaba: 		}
4fd800b3a8 2011-02-23        kinaba: 		--size;
4fd800b3a8 2011-02-23        kinaba: 	}
4fd800b3a8 2011-02-23        kinaba: };
4fd800b3a8 2011-02-23        kinaba: 
4fd800b3a8 2011-02-23        kinaba: // BEGIN CUT HERE
4fd800b3a8 2011-02-23        kinaba: #include <ctime>
4fd800b3a8 2011-02-23        kinaba: double start_time; string timer()
4fd800b3a8 2011-02-23        kinaba:  { ostringstream os; os << " (" << int((clock()-start_time)/CLOCKS_PER_SEC*1000) << " msec)"; return os.str(); }
4fd800b3a8 2011-02-23        kinaba: template<typename T> ostream& operator<<(ostream& os, const vector<T>& v)
4fd800b3a8 2011-02-23        kinaba:  { os << "{ ";
4fd800b3a8 2011-02-23        kinaba:    for(typename vector<T>::const_iterator it=v.begin(); it!=v.end(); ++it)
4fd800b3a8 2011-02-23        kinaba:    os << '\"' << *it << '\"' << (it+1==v.end() ? "" : ", "); os << " }"; return os; }
4fd800b3a8 2011-02-23        kinaba: void verify_case(const double& Expected, const double& Received) {
4fd800b3a8 2011-02-23        kinaba:  bool ok = (abs(Expected - Received) < 1e-9);
4fd800b3a8 2011-02-23        kinaba:  if(ok) cerr << "PASSED" << timer() << endl;  else { cerr << "FAILED" << timer() << endl;
4fd800b3a8 2011-02-23        kinaba:  cerr << "\to: \"" << Expected << '\"' << endl << "\tx: \"" << Received << '\"' << endl; } }
4fd800b3a8 2011-02-23        kinaba: #define CASE(N) {cerr << "Test Case #" << N << "..." << flush; start_time=clock();
4fd800b3a8 2011-02-23        kinaba: #define END	 verify_case(_, RabbitStepping().getExpected(field, r));}
4fd800b3a8 2011-02-23        kinaba: int main(){
4fd800b3a8 2011-02-23        kinaba: 
4fd800b3a8 2011-02-23        kinaba: CASE(0)
4fd800b3a8 2011-02-23        kinaba: 	string field = "WRBRW";
4fd800b3a8 2011-02-23        kinaba: 	int r = 4;
4fd800b3a8 2011-02-23        kinaba: 	double _ = 0.8;
4fd800b3a8 2011-02-23        kinaba: END
4fd800b3a8 2011-02-23        kinaba: CASE(1)
4fd800b3a8 2011-02-23        kinaba: 	string field = "WWB";
4fd800b3a8 2011-02-23        kinaba: 	int r = 2;
4fd800b3a8 2011-02-23        kinaba: 	double _ = 1.3333333333333333;
4fd800b3a8 2011-02-23        kinaba: END
4fd800b3a8 2011-02-23        kinaba: CASE(2)
4fd800b3a8 2011-02-23        kinaba: 	string field = "WW";
4fd800b3a8 2011-02-23        kinaba: 	int r = 1;
4fd800b3a8 2011-02-23        kinaba: 	double _ = 1.0;
4fd800b3a8 2011-02-23        kinaba: END
4fd800b3a8 2011-02-23        kinaba: CASE(3)
4fd800b3a8 2011-02-23        kinaba: 	string field = "BBBBBBBBBB";
4fd800b3a8 2011-02-23        kinaba: 	int r = 4;
4fd800b3a8 2011-02-23        kinaba: 	double _ = 0.9523809523809523;
4fd800b3a8 2011-02-23        kinaba: END
4fd800b3a8 2011-02-23        kinaba: CASE(4)
4fd800b3a8 2011-02-23        kinaba: 	string field = "RRBRRWRRBRRW";
4fd800b3a8 2011-02-23        kinaba: 	int r = 8;
4fd800b3a8 2011-02-23        kinaba: 	double _ = 0.9696969696969697;
4fd800b3a8 2011-02-23        kinaba: END
4fd800b3a8 2011-02-23        kinaba: CASE(5)
4fd800b3a8 2011-02-23        kinaba: 	string field = "RRRRRRRRRRRRRRRRR";
4fd800b3a8 2011-02-23        kinaba: 	int r = 8;
4fd800b3a8 2011-02-23        kinaba: 	double _ = -1;
4fd800b3a8 2011-02-23        kinaba: END
4fd800b3a8 2011-02-23        kinaba: CASE(6)
4fd800b3a8 2011-02-23        kinaba: 	string field = "BBBBBBBBBBBBBBBBB";
4fd800b3a8 2011-02-23        kinaba: 	int r = 8;
4fd800b3a8 2011-02-23        kinaba: 	double _ = -1;
4fd800b3a8 2011-02-23        kinaba: END
4fd800b3a8 2011-02-23        kinaba: CASE(7)
4fd800b3a8 2011-02-23        kinaba: 	string field = "WWWWWWWWWWWWWWWWW";
4fd800b3a8 2011-02-23        kinaba: 	int r = 8;
4fd800b3a8 2011-02-23        kinaba: 	double _ = -1;
4fd800b3a8 2011-02-23        kinaba: END
4fd800b3a8 2011-02-23        kinaba: CASE(8)
4fd800b3a8 2011-02-23        kinaba: 	string field = "BWBWBWBWBWBWBWBWB";
4fd800b3a8 2011-02-23        kinaba: 	int r = 8;
4fd800b3a8 2011-02-23        kinaba: 	double _ = -1;
4fd800b3a8 2011-02-23        kinaba: END
4fd800b3a8 2011-02-23        kinaba: CASE(9)
4fd800b3a8 2011-02-23        kinaba: 	string field = "RR";
4fd800b3a8 2011-02-23        kinaba: 	int r = 2;
4fd800b3a8 2011-02-23        kinaba: 	double _ = 2;
4fd800b3a8 2011-02-23        kinaba: END
4fd800b3a8 2011-02-23        kinaba: CASE(9)
4fd800b3a8 2011-02-23        kinaba: 	string field = "RR";
4fd800b3a8 2011-02-23        kinaba: 	int r = 1;
4fd800b3a8 2011-02-23        kinaba: 	double _ = 1;
4fd800b3a8 2011-02-23        kinaba: END
4fd800b3a8 2011-02-23        kinaba: CASE(9)
4fd800b3a8 2011-02-23        kinaba: 	string field = "BRWWBRBWBWBWBRBWR";
4fd800b3a8 2011-02-23        kinaba: 	int r = 1;
4fd800b3a8 2011-02-23        kinaba: 	double _ = 1;
4fd800b3a8 2011-02-23        kinaba: END
4fd800b3a8 2011-02-23        kinaba: }
4fd800b3a8 2011-02-23        kinaba: // END CUT HERE