MHB Solve Bob's Granny's Old Cipher Mystery

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Bob discovers an old box in his granny's cellar containing encrypted messages, including one partially readable message: IEHMTALVOHETMAIVLO. His granny explains the decryption principle, stating that the code should be divided into two equal parts, which correspond to the pre-order and in-order traversals of a binary tree. To decode the message, Bob needs to construct the binary tree and read it in reverse post-order. His granny notes that each letter appears only once in each part, simplifying the decryption process. Bob seeks further clarification to use the cipher for messaging Alice.
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Bob has found in his granny's cellar an old box with strange messages inside. Most of them are almost unreadable since the paper is very old. His granny is very happy since she believed this box was lost. she remembers when she was a student in mathematics, she was using a secret cipher to correspond with her boyfriend. The box contains some encrypted messages. One of the messages is still readable: IEHMTALVOHETMAIVLOBob is fascinated and asks his granny to decrypt it, but the old lady only accepts to explain him the main principle of the cipher: `` if you want to read it you must deserve it’’, she said. ``But it is simple: divide the code into two equal parts and verify that both parts contain the same letters. The first part corresponds to a pre-order while the second corresponds to an in-order of a binary tree. Find the related binary tree and read it in reverse post-order.’’

After reading carefully the message she adds: You are lucky, here each letter occurs only once in each part. I remember we invented a specific code when there were several occurrences of the same letter with possible ambiguity.`Bob is quite confused and asks more details but she refuses to help him more. She still likes to play. Bob would like to understand well in order to use this cipher for sending messages to Alice. Can you help him understand this message?
 
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Erm...
HTAMEVOLI?
 
I like Serena said:
Erm...
HTAMEVOLI?
For the related binary tree, I get:
I
EL
HMVO
TA

They want the reverse post-order, so ILOVEMATH.
 
sadsadsadsa said:
Bob has found...

Enough time has passed that you may now post your solution. (Yes)
 
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