risk.r

# RISK Attack Simulation

attack <- function(na, nb) {
    die <- 1:6
    while (na > 0 & nb > 0) {
        attackers <- min(na, 3)
        defenders <- min(nb, 2)
        fights <- min(attackers, defenders)

        hit_a <- sort(sample(die, attackers), decreasing=T)[1:fights]
        hit_b <- sort(sample(die, defenders), decreasing=T)[1:fights]
        
        victories_a <- sum(hit_a >  hit_b)
        victories_b <- sum(hit_a <= hit_b)
        na <- na - victories_b
        nb <- nb - victories_a
    }
    na > 0
}

probVictory <- function(na, nb) {
    n <- 1000
    sum(replicate(n, attack(na, nb), "array")) / n * 100
}