【POJ 3071】 Football

【题目链接】
【算法】
概率DP
f[i][j]表示第j支队伍进入第i轮的概率,转移比较显然
【代码】
#include <algorithm>
#include <bitset>
#include <cctype>
#include <cerrno>
#include <clocale>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
#include <deque>
#include <exception>
#include <fstream>
#include <functional>
#include <limits>
#include <list>
#include <map>
#include <iomanip>
#include <ios>
#include <iosfwd>
#include <iostream>
#include <istream>
#include <ostream>
#include <queue>
#include <set>
#include <sstream>
#include <stdexcept>
#include <streambuf>
#include <string>
#include <utility>
#include <vector>
#include <cwchar>
#include <cwctype>
#include <stack>
#include <limits.h>
using namespace std;

int i,j,k,n,pos;
double a[300][300],f[10][300];

int main() 
{
        
        while (scanf("%d",&n) != EOF && n != -1)
        {
                memset(f,0,sizeof(f));
                for (i = 1; i <= (1 << n); i++)
                {
                        for (j = 1; j <= (1 << n); j++)
                        {
                                scanf("%lf",&a[i][j]);
                        }
                }        
                for (i = 1; i <= (1 << n); i++) f[1][i] = 1.0;
                for (i = 2; i <= n + 1; i++)
                {
                        for (j = 1; j <= (1 << n); j++)
                        {
                                for (k = 1; k <= (1 << n); k++)
                                { 
                                        if ((((j - 1) >> (i - 2)) ^ 1) == ((k - 1) >> (i - 2)))
                                                f[i][j] += f[i-1][k] * f[i-1][j] * a[j][k];     
                                }
                        }
                }
                pos = 0;
                for (i = 1; i <= (1 << n); i++)
                {
                        if (f[n+1][i] > f[n+1][pos])
                                pos = i;
                } 
                printf("%d
",pos);
        }
            
        return 0;
}