Level2 - 가장 큰 수(Swift)

func solution(_ numbers:[Int]) -> String {
    
    var result = numbers.sorted() { (left, right)  in
        let a = Int(String(left) + String(right))
        let b = Int(String(right) + String(left))
        print(a,b)
        return a! > b!
    }
    
    if result.first == 0 {
        result = [0]
    }
    
    return result.map{String($0)}.joined()
   
}

print(solution([6,10,2]))
print(solution([0,0,0,0]))