I’m trying to write a short Julia program to solve the n queens problem – where you try place n queens on an nxn chess board such that they don’t attack each other – I am new to Julia and I don’t understand why the error “MethodError: no method matching check(::Int64, ::Int64, ::Int64, ::BitMatrix)” is given when check is defined with argument types for the variable types desired.

I’ve tried to detail the variable types more within the function and prior to passing the values, but it still tries to find a method with different data types.

code listed below

solve(1, 6, falses(6, 6))
display(board)



function check(row::Int16, column::Int16, n::Int16, board::BitMatrix)
    left::Int16 = 0
    checkLeft::Bool = true
    right::Int16 = 0
    checkRight::Bool = true
    for j::Int16 = row:-1:1
        if left==column-1
            checkLeft = false
        else
            left+=1
        end
        if right==n-column
            checkRight = false
        else
            right+=1
        end
        if board[j,column]||(board[j,column-left]&&checkLeft)||(board[j,column+right]&&checkRight)
            return true
        end
    end
    return false
end

function solve(row::Int16, n::Int16, board::BitMatrix)
    column::Int16 = 1
    if row>=n
        return true
    end
    for column = 1:n
        if check(row, column, n, board)
            board[row,column] = true
            if solve(row+1, n, board)
                return true
            end
            board[row,column] = false
        else
            column+=1
        end
    end
    return false
end