given an array of strings, string only contains 0 and 1.
for each pair of string, we find the first un-macth characters (from left to right), suppose the length of first string from the un-matched character to the end is A, the length of second from the un-matched character to the end is B.
try to find the max sum of A + B.

for example,
"01011100"
"010101010101"
A is 4, B is 8 , then the sum is 12.

calculate this kind of sum for each pair of strings in the array, return the max one.
Note: trie is denied by the interviewer.