[1,2,3,2,1,2,3,3] -> [3,7,8]
[1, 2, 3, 1, 4, 4, 4, 2, 5] -> {2: [1, 2], 3: [4], 1: [3, 5]}
["aba","otto","aba"]
["aba","otto","bab"]
["aba","otot","aba"]
a
b