Game of guessing the correct number, No.2(HIT-AND-BLOW)

[Introduction]

The right name of this game is probably "HIT-AND-BLOW".

[What is needed]

There are only paper and a pencil needed.

[How to play]

This is a win-loss game between two players. One of the players should image a number of four figures, and the other should guess that number. Repeating this process one after the other, the player who can first correctly guess the other's number imagined should become a winner.

[A number of four figures]

It should be made up of nine figures from 1 through 9, but the same figure should not appear in this number. For example, "5253" is illegal because "5" appears twice in this number.

[Game]

For example, below is described the case where you (A) imagine 4831 and the opponent (B) 9127.
First, (A) declares (B), for example, 1234. Comparing 9127 with 1234, (B) tells (A) its evaluation. In turn, (A) guesses (B)'s number using that evaluation.
Next, (B) declares (A), for example, 4567. Comparing 4831 with 4567, (A) tells (B) its evaluation. In turn, (B) guesses (A)'s number using that evaluation.
Alternatively repeating this process, the player should try to correctly guess the other's number first.

[How to express evalutions]

For example, below is described the case where (B) images 9127.
When (A) declares 1234, the evaluation should be "2B" because two figures 1 and 2 are correctly guessed and yet wrongly placed.
When (A) declares 7385, the evaluation "B" because 7 is correctly guessed and yet wrongly placed.
When (A) declares 8173, the evaluation "HB" because 7 is correctly guessed and yet wrongly placed as well as 1 being correctly guessed and placed.
When (A) declares 9173, the evaluation "2HB" because 7 is correctly guessed and yet wrongly placed as well as two figures 1 and 9 being correctly guessed and placed.
When (A) declares 2174, the evaluation "H2B" because two figures 2 and 7 are correctly guessed and yet wrongly placed as well as 1 being correctly guessed and placed.
When (A) declares 5127, the evaluation "3H" because three figures 1, 2 and 7 are correctly guessed and placed.

[Advisory Technique]

If you first declare the opponent 4672 and get "2B" and next declare 3891 and get "B", then 5 never fails to exist.

[Postscript]

Usually you will be able to guess the correct number after six or seven declarations.

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