In the morning, I swiped a password puzzle, and suddenly felt like the feeling of pondering the structure of the lock cylinder when I forgot to bring the key - the title said that there was a three-digit password, and gave three clues, let's take a plate together:

First of all, Correct topic clues

318: 1 number in the right position is correct 1379: 1 number is correct but in the wrong place863: 2 numbers are correct but all in the wrong place421: None of the numbers are correct

Second, crack the key: use the elimination method to reverse the position

❶Sift out the absolutely wrong numbers first

From clue 4 "421 is all wrong", the numbers 4, 2, and 1 are excludedClue 3 "863 has 2 correct numbers", possible combinations: 8(x)6, 8(x)3, 6(x)3, but in combination with other clues

❷ Exclusion of the possibility of 3

Suppose clue 3 contains 3:

If 3 is correct, then 3 in clue 1 "318" is in the first place (position pair), but it contradicts clue 2, so 3 is wrongTherefore, the correct number of line 3 is 8(x)6, excluding 3

❸Lock in the correct number pool

Excluded: 3, 4, 2, 1The correct digits are in 8, 6, 7, and 9, and if clue 3 confirms that 8 and 6 are correct, and 379 in clue 2 excludes 3, the correct number is 1 of 7 or 9

❹ Deriving Position (Critical 3 Steps)

3 and 1 in clue 1 "318" are wrong, only 8 is correct, and 8 is in the wrong position (8 is not in the first place because 8 is wrong in the first place in clue 3)

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