Given a list of strings string_list, return the maximum value of len(string_list[i]) * len(string_list[j]) for any two distinct strings string_list[i] and string_list[j] that do not share any common characters. If no such pair exists, return 0.
Example 1
Input: [abcd,efgh,ijkl]
Output: 16
Explanation: abcd and efgh do not share any letters, product is 4*4=16.
Example 2
Input: [abc,def,ghij,klm]
Output: 12
Explanation: def and ghij do not share any letters, product is 3*4=12.
Example 3
Input: [aa,bb,cc,dd]
Output: 4
Explanation: Any two strings do not share letters, product is 2*2=4.
Example 4
Input: [abc,bcd,cde]
Output: 0
Explanation: All pairs share at least one letter.
Constraints
Case 1
Input: ['mnop','qrst','uvwx','yz']
Expected: 16
Case 2
Input: ['a','b','c','d']
Expected: 1
Case 3
Input: ['abc','defg','hijk','lmno']
Expected: 16
Case 4
Input: ['abc','abc','abc']
Expected: 0
Case 5
Input: ['ab','cd','ef','gh']
Expected: 4