codeforces105d Bag of mice ——概率DP

Link:

http://codeforces.com/problemset/problem/148/D

Refer to:

http://www.cnblogs.com/kuangbin/archive/2012/10/04/2711184.html

 #include <iostream>
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
 #include <cmath>
 #include <cctype>
 #include <algorithm>
 #include <queue>
 #include <deque>
 #include <queue>
 #include <list>
 #include <map>
 #include <set>
 #include <vector>
 #include <utility>
 #include <functional>
 #include <fstream>
 #include <iomanip>
 #include <sstream>
 #include <numeric>
 #include <cassert>
 #include <ctime>
 #include <iterator>
 const int INF = 0x3f3f3f3f;
 ][] = {{-,},{,},{,-},{,},{-,-},{-,},{,-},{,}};
 using namespace std;
 ][];
 int main(void)
 {
     int w,b;
     #ifndef ONLINE_JUDGE
     freopen("in.txt","r",stdin);
     #endif // ONLINE_JUDGE
     while (~scanf("%d%d",&w,&b))
     {
         ;i<=w;++i);j<=b;++j)a[i][j]=;
         ;i<=b;++i) a[][i]=;
         ;j<=w;++j) a[j][]=;
         ;i<=w;++i)
         {
             ;j<=b;++j)
             {
                 a[i][j]+=(double)i/(i+j);
                 )
                     a[i][j]+=a[i][j-]*(double)j/(i+j)
                     *()/(i+j-)
                     *()/(i+j-);
                 )
                     a[i][j]+=a[i-][j-]*(double)j/(i+j)
                     *()/(i+j-)
                     *();
             }
         }
         printf("%.9lf\n",a[w][b]);
     }
     ;
 }

这题很有意思。为什么自己想不出来？