<jupyter_start><jupyter_text>You are given a license key represented as a string S which consists only alphanumeric character and dashes. The string is separated into N+1 groups by N dashes.Given a number K, we would want to reformat the strings such that each group contains exactly K characters, except for the first group which could be shorter than K, but still must contain at least one character. Furthermore, there must be a dash inserted between two groups and all lowercase letters should be converted to uppercase.Given a non-empty string S and a number K, format the string according to the rules described above.Example 1:Input: S = "5F3Z-2e-9-w", K = 4Output: "5F3Z-2E9W" Explanation: The string S has been split into two parts, each part has 4 characters.Note that the two extra dashes are not needed and can be removed.Example 2:Input: S = "2-5g-3-J", K = 2Output: "2-5G-3J"Explanation: The string S has been split into three parts, each part has 2 characters except the first part as it could be shorter as mentioned above.Note:The length of string S will not exceed 12,000, and K is a positive integer.String S consists only of alphanumerical characters (a-z and/or A-Z and/or 0-9) and dashes(-).String S is non-empty.<jupyter_code>#BRUTEFORCE
def key_formatting(ls,k):
    keys=ls.replace("-","")
    tail =len(keys)-1
    op=[]
    while tail >=0:
        op.append(keys[tail])
        if tail !=0 and (tail % k) ==0:
            op.append("-")
        tail -=1
    return ''.join(map(str, op[::-1])).upper()
print(key_formatting("<KEY>",2))
#Note the aove solution does not pass one use case
# when input is 2-5g-3-J
def key_formatting(ls,k):
    keys=ls.replace("-","")[::-1].upper()
    tail =len(keys)-1
    op=[]
    while tail >=0:
        op.append(keys[tail])
        if tail !=0 and (tail % k) ==0:
            op.append("-")
        tail -=1
    return ''.join(map(str, op))
print(key_formatting("2-5g-3-J",2))<jupyter_output>2-5G-3J