poj 1322 Chocolate (概率dp)

poj 1322 Chocolate (概率dp)

///有c種不同顏色的巧克力，一個個的取，當發現有相同的顏色的就吃掉，去了n個後，到最後還剩m個的概率
///dp[i][j]表示取了i個還剩j個的概率
///當m+n為奇時，概率為0
# include 
# include 
# include 
# include 
using namespace std;
double dp[1010][1010];
int main()
{

   int i,j,n,m,c;
    while(~scanf("%d",&c),c)
    {
        scanf("%d%d",&n,&m);
        if(m>c||m>n||(n+m)%2)
            printf("0.000\n");
        else
        {
            if(n>1000)
              n=1000+n%2;
            memset(dp,0,sizeof(dp));
            dp[0][0]=1;
            for(i=1;i<=n;i++)
            {

                dp[i][0]=dp[i-1][1]/c;
                dp[i][c]=dp[i-1][c-1]/c;
                for(j=1;j