uva 10648 - Red Huang

排列组合概率 DP

这部分还是不太熟悉，网络上的做法

3 3
[1][][] (1,1)=1
[12][][] (2,1)=1/3 [1][2][],[1][][2] (2,2)=2/3
[123][][] (3,1)=1/9 [12][3][],[12][][3] (3,2)=2/9
[13][2][],[1][23][],[13][][2],[1][][23] (3,2)=4/9
[1][2][3],[1][3][2] (3,3)=2/9

//====================================================================||  
//                                                                    ||  
//                                                                    ||  
//                         Author : GCA                               ||  
//                  6AE7EE02212D47DAD26C32C0FE829006                  ||  
//====================================================================||  
#include <iostream>  
#include <cstdio>  
#include <cstring>  
#include <algorithm>  
#include <cmath>  
#include <climits>  
#include <vector>  
#include <set>  
#include <map>  
#include <queue>  
#include <cctype>  
#include <utility>  
using namespace std;  
#ifdef ONLINE\_JUDGE  
#define ll "%lld"  
#else  
#define ll "%I64d"  
#endif  
typedef unsigned int uint;  
typedef long long int Int;  
#define Set(a,s) memset(a,s,sizeof(a))  
#define Write(w) freopen(w,"w",stdout)  
#define Read(r) freopen(r,"r",stdin)  
#define Pln() printf("\\n")  
#define I\_de(x,n)for(int i=0;i<n;i++)printf("%d ",x\[i\]);Pln()  
#define De(x)printf(#x"%d\\n",x)  
#define For(i,x)for(int i=0;i<x;i++)  
#define CON(x,y) x##y  
#define Pmz(dp,nx,ny)for(int hty=0;hty<ny;hty++){for(int htx=0;htx<nx;htx++){\\  
    printf("%d ",dp\[htx\]\[hty\]);}Pln();}  
#define M 55  
#define PII pair<int,int\>  
#define PB push\_back  
#define oo INT\_MAX  
#define Set\_oo 0x3f  
#define Is\_debug true  
#define debug(...) if(Is\_debug)printf("DEBUG: "),printf(\_\_VA\_ARGS\_\_)  
#define FOR(it,c) for(\_\_typeof((c).begin()) it=(c).begin();it!=(c).end();it++)  
#define eps 1e-6  
bool xdy(double x,double y){return x>y+eps;}  
bool xddy(double x,double y){return x>y-eps;}  
bool xcy(double x,double y){return x<y-eps;}  
bool xcdy(double x,double y){return x<y+eps;}  
int min3(int x,int y,int z){  
    int tmp=min(x,y);  
    return min(tmp,z);  
}  
int max3(int x,int y,int z){  
    int tmp=max(x,y);  
    return max(tmp,z);  
}  
int n,m;  
int main() {  
    ios\_base::sync\_with\_stdio(0);  
    int ff=0;  
    while(scanf("%d%d",&n,&m)==2){  
        double dp\[105\]\[105\];  
        Set(dp,0);  
        dp\[0\]\[0\]=1.0;  
        for(int i=0;i<=n;i++){  
            for(int j=0;j<=m;j++){  
                dp\[i+1\]\[j\]+=dp\[i\]\[j\]\*(1.0\*j/m);  
                dp\[i+1\]\[j+1\]+=dp\[i\]\[j\]\*(1.0\*(m-j)/m);  
            }  
        }  
        printf("Case %d: %.7f\\n",++ff,1-dp\[n\]\[m\]);  
    }  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
}