Solves the puzzle in COD Warzone

CODWarzoneSolver.R

library(stringr)
solve <- function(code) {
    
    # Extract the num
    nums <- as.numeric(strsplit(gsub("[A-Z]", "", code), '')[[1]])
    letters <- unique(strsplit(gsub("[0-9]", "", code), "")[[1]])
    miss_nums <- setdiff(seq(1, 9), nums)
    
    # Generate all permutations of possible solution numbers
    # No permutation function in R so make my own
    perms <- miss_nums
    for (i in 1:(length(letters) - 1)) {
        perms <- cbind(perms, miss_nums)
    }
    perms <- expand.grid(as.data.frame(perms))
    # Remove all entries where number appears more than once
    n_unique <- apply(perms, 1, function(x) length(unique(x)))
    perms <- perms[n_unique == ncol(perms), ]
    
    perms 
    
    for (i in 1:nrow(perms)) {
        attempt <- str_replace_all(code, setNames(as.character(perms[i, ]), letters))
        attempt_pt1 <- substr(attempt, 1, 4)
        attempt_pt2 <- substr(attempt, 5, 8)
        cat(sprintf("Attempt %d/%d: %s\t%s\n\n", i, nrow(perms), attempt_pt1, attempt_pt2))
        readline()
    }
}

code <- 'H5NN6C4H'
solve('H5NN6C4H')