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Problem of the Week
Problem A
Secret Message

Alicia and Bao want to send messages to each other without other people being able to read them. They set up a code that uses just 0s and 1s in the message. To decode the message it takes two steps:

  1. Read the message, 4 digits at a time. Then look up each 4-digit code in the tables below and replace it with the given lowercase letter.

    Code 0000 0001 0010 0011 0100 0101 0110 0111
    Letter a b c d e f g h

    Code 1000 1001 1010 1011 1100 1101 1110 1111
    Letter i j k l m n o p

  2. Read the new message, two consecutive letters at a time. Then look up each pair of lowercase letters in the tables below and replace them with the given uppercase letter. The word formed by these uppercase letters is the secret message.

Lowercase Letters eb ec ed ee ef eg eh ei ij ek el em en
Uppercase Letter A B C D E F G H I J K L M

Lowercase Letters eo ep fa fb fc fd fe ff fg fh fi fj fk
Uppercase Letter N O P Q R S T U V W X Y Z

For example, if Alicia sent the code 0100111101001011, after the first step the message becomes epel, and after the second step Bao knows the message is OK.

Decode the following message:

01010010010001010101001101010000010001010100001101010100

Try writing and sending secret messages of your own.

Theme: Computational Thinking