Artifact 1b625ac1477fd5f00c4eee688cd288ac5ca16ec9
#include <iostream>
#include <sstream>
#include <iomanip>
#include <vector>
#include <string>
#include <map>
#include <set>
#include <algorithm>
#include <numeric>
#include <iterator>
#include <functional>
#include <complex>
#include <queue>
#include <stack>
#include <cmath>
#include <cassert>
#include <cstring>
using namespace std;
typedef long long LL;
typedef complex<double> CMP;
int bitcnt(int m)
{
int c = 0;
for(;m;m>>=1)
c += (m&1);
return c;
}
class RabbitStepping { public:
double getExpected(string field, int r)
{
cerr<<field.size()<<endl;
int ex = 0;
int cn = 0;
int N = field.size();
for(int mask=1; mask<(1<<N); ++mask)
if( bitcnt(mask) == r )
{
vector< pair<int,int> > rs;
for(int i=0; i<N; ++i)
if( mask & (1<<i) )
rs.push_back(make_pair(-1,i));
int left = run(field, rs, N);
ex += left;
cn += 1;
}
return double(ex) / cn;
}
int run(const string& field, vector< pair<int,int> >& rs, int size)
{
while( size > 2 && !rs.empty() )
{
oneStep(field, rs, size);
int cnt[20] = {};
for(int i=0; i<rs.size(); ++i)
cnt[rs[i].second] ++;
vector< pair<int,int> > rs2;
for(int i=0; i<rs.size(); ++i)
if( cnt[rs[i].second] == 1 )
rs2.push_back(rs[i]);
rs.swap(rs2);
}
return rs.size();
}
void oneStep(const string& field, vector< pair<int,int> >& rs, int& size)
{
for(int i=0; i<rs.size(); ++i) {
int prev = rs[i].first;
int& cur = rs[i].second;
rs[i].first = cur;
if( cur == 0 )
cur ++;
else if( cur >= size-2 )
cur --;
else if( field[cur]=='W' )
cur --;
else if( field[cur]=='B' )
cur ++;
else if( prev == -1 )
cur --;
else
cur = prev;
}
--size;
}
};
// BEGIN CUT HERE
#include <ctime>
double start_time; string timer()
{ ostringstream os; os << " (" << int((clock()-start_time)/CLOCKS_PER_SEC*1000) << " msec)"; return os.str(); }
template<typename T> ostream& operator<<(ostream& os, const vector<T>& v)
{ os << "{ ";
for(typename vector<T>::const_iterator it=v.begin(); it!=v.end(); ++it)
os << '\"' << *it << '\"' << (it+1==v.end() ? "" : ", "); os << " }"; return os; }
void verify_case(const double& Expected, const double& Received) {
bool ok = (abs(Expected - Received) < 1e-9);
if(ok) cerr << "PASSED" << timer() << endl; else { cerr << "FAILED" << timer() << endl;
cerr << "\to: \"" << Expected << '\"' << endl << "\tx: \"" << Received << '\"' << endl; } }
#define CASE(N) {cerr << "Test Case #" << N << "..." << flush; start_time=clock();
#define END verify_case(_, RabbitStepping().getExpected(field, r));}
int main(){
CASE(0)
string field = "WRBRW";
int r = 4;
double _ = 0.8;
END
CASE(1)
string field = "WWB";
int r = 2;
double _ = 1.3333333333333333;
END
CASE(2)
string field = "WW";
int r = 1;
double _ = 1.0;
END
CASE(3)
string field = "BBBBBBBBBB";
int r = 4;
double _ = 0.9523809523809523;
END
CASE(4)
string field = "RRBRRWRRBRRW";
int r = 8;
double _ = 0.9696969696969697;
END
CASE(5)
string field = "RRRRRRRRRRRRRRRRR";
int r = 8;
double _ = -1;
END
CASE(6)
string field = "BBBBBBBBBBBBBBBBB";
int r = 8;
double _ = -1;
END
CASE(7)
string field = "WWWWWWWWWWWWWWWWW";
int r = 8;
double _ = -1;
END
CASE(8)
string field = "BWBWBWBWBWBWBWBWB";
int r = 8;
double _ = -1;
END
CASE(9)
string field = "RR";
int r = 2;
double _ = 2;
END
CASE(9)
string field = "RR";
int r = 1;
double _ = 1;
END
CASE(9)
string field = "BRWWBRBWBWBWBRBWR";
int r = 1;
double _ = 1;
END
}
// END CUT HERE