XJOI网上同步训练DAY6 T2

Posted 2020-08-02 GFY

思路:记得FJ省队集训好像有过这题，可是我太弱了，根本不懂T_T

 1 #include<cstdio>
 2 #include<iostream>
 3 #include<cmath>
 4 #include<cstring>
 5 #include<algorithm>
 6 int n,m;
 7 double f[1005][1005];
 8 int pd[1005][1005];
 9 int read(){
10     int t=0,f=1;char ch=getchar();
11     while (ch<\'0\'||ch>\'9\'){if (ch==\'-\')f=-1;ch=getchar();}
12     while (\'0\'<=ch&&ch<=\'9\'){t=t*10+ch-\'0\';ch=getchar();}
13     return t*f;
14 }
15 void dfs(int n,int m){
16     if (pd[n][m]) return;
17     pd[n][m]=1;
18     if (n==0||m==0) f[n][m]=(1.0)/(m+1);else{
19         dfs(m-1,n);dfs(m,n-1);
20         double x,y,x1,y1;
21         x=m/(m+1.0)*(1-f[m-1][n])-1,y=1;
22         x1=m/(m+1.0)*(1-f[m-1][n])+1.0/(m+1)+(f[m][n-1]-1);
23         y1=1-f[m][n-1];
24         double a=(y1-y)/(x-x1);
25         f[n][m]=a*x1+y1;
26     }
27 }
28 int main(){
29     n=read();m=read();
30     dfs(n,m);
31     printf("%.10f %.10f\\n",f[n][m],1-f[n][m]);
32 }