MAP <- function(x) { # モード値を計算
dens <- density(x)
mode_i <- which.max(dens$y)
mode_x <- dens$x[mode_i]
mode_y <- dens$y[mode_i]
c(x=mode_x, y=mode_y)
}

Na=1000 ; Nb=1000
pa=0.1 ; pb=0.01
Wa=100 ; Wb=1000
n=100
A0=c(rep(1,Na*pa),rep(0,Na-Na*pa))
B0=c(rep(1,Nb*pb),rep(0,Nb-Nb*pb))

Get <- function(a){ #Aをa本買ったときの賞金合計
sum(sample(A0,a))*Wa + sum(sample(B0,n-a))*Wb
}

takarakuji <- function(k=10^3,Histogram=FALSE,Print=TRUE,...){
MAX=replicate(k,which.max(sapply(aa,Get))-1)
if(Histogram) {hist(MAX,freq=FALSE,...) ; lines(density(MAX),lwd=2)}
if(Print)print(round(c(mean=mean(MAX),sd=sd(MAX),mode=MAP(MAX)[1]),2))
invisible(c(mean=mean(MAX),sd=sd(MAX),mode=MAP(MAX)[1]))
}

takarakuji(10^5,Histogram = TRUE,col='lightblue')