Excel精确匹配可搜索矩阵(Excel exact match searchable matrix)

 是的，你错过了什么。 不，那不是正确答案:-) 
 
 原始计算的密码长度恰好为八个字符，而不是八个或更少的密码。 
 
 对于可以在4到8个字符之间的密码，实际上比原始计算中的搜索空间更多（不是因为搜索空间越少等于花费更多时间，而是因为原始计算错误）。 
 
 对于一到八个字符的密码，搜索空间实际上是： 
 
(62 ^ 1) + (62 ^ 2) + (62 ^ 3) + (62 ^ 4) +
(62 ^ 5) + (62 ^ 6) + (62 ^ 7) + (62 ^ 8)
 
 然后你可以将它除以2来进行平均检查次数（我不会因为我们实际上只讨论比率）。 
 
 然后，如果您有额外的信息，密码长度至少为四个字符，您可以折扣前三个条款得到： 
 
                                 (62 ^ 4) +
(62 ^ 5) + (62 ^ 6) + (62 ^ 7) + (62 ^ 8)

Yes, you are missing something. No, that's not the correct answer :-)
 
Your original calculation is for a password that is exactly eight characters long, not one that is eight or less.
 
For a password which can be between four and eight characters, there's actually more search space than in your original calculation (not because less search space equates to more time taken, but because the original calculation was wrong).
 
For a password of one to eight characters, the search space is actually:
 
(62 ^ 1) + (62 ^ 2) + (62 ^ 3) + (62 ^ 4) +
(62 ^ 5) + (62 ^ 6) + (62 ^ 7) + (62 ^ 8)
 
and then you can divide that by two for the average number of checks (I won't since we're really only talking about ratios here).
 
Then, if you have the extra information that the password is at least four characters long, you can discount the first three terms to get:
 
                                 (62 ^ 4) +
(62 ^ 5) + (62 ^ 6) + (62 ^ 7) + (62 ^ 8)