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Difficulty: MediumCoding and Decoding

In a covert military operation, communication officers use a specific cryptographic algorithm to secure tactical locations. If the location BRIDGE is encoded as VTWRIY, which of the following represents the code for the location HARBOR?

  1. ILYIZSAnswer
  2. B
    SZIYLI
  3. C
    HKXHYR
  4. D
    HLYHZS

Answer

The cryptographic code for HARBOR is ILYIZS.
The correct answer accurately applies both steps of the established encryption algorithm: first replacing each letter in HARBOR with its alphabetical opposite (yielding SZIYLI), and then completely reversing the resulting string to arrive at ILYIZS.

Step-by-Step Solution

1
Determine the transformation rule applied to the letters of the given word BRIDGE.
Each letter is replaced by its opposite in the alphabet (Reverse Alphabetical Index, where A=Z, B=Y, etc.). B(2) becomes Y(25), R(18) becomes I(9), I(9) becomes R(18), D(4) becomes W(23), G(7) becomes T(20), and E(5) becomes V(22). The resulting sequence is YIRWTV.
Establishing the initial letter substitution mapping is the first step in decoding the algorithm.
2
Compare the sequence of opposite letters to the final encrypted code.
The intermediate sequence YIRWTV is reversed to become VTWRIY, matching the given code.
Identifying any secondary transformations (like string reversal) ensures the complete algorithm is understood.
3
Apply the reverse alphabetical index to the target word HARBOR.
H(8) becomes S(19), A(1) becomes Z(26), R(18) becomes I(9), B(2) becomes Y(25), O(15) becomes L(12), and R(18) becomes I(9). The intermediate sequence is SZIYLI.
This executes the first half of the decoded algorithmic rule on the required word.
4
Apply the string reversal to the intermediate sequence.
Reversing SZIYLI results in ILYIZS.
This executes the final step of the algorithm to obtain the exact encrypted code.

Key Concept

Reverse Alphabetical Indexing and String Reversal
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Topics

Coding and Decoding

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