1088. Confusing Number II #324
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| char first = s.charAt(0); | ||
| int res = count(first) * (int) (Math.pow(5, s.length() - 1)); |
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What is being done here?
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findTotal is to calculate the total count of the numbers which can be generated using those five numbers: 0, 1, 6, 8, 9.
It is why we use 5 to calculate the permutation.
As the "s" is a limit for us, we have to calculate numbers less than "s".
In order to do that: count(first) returns the numbers less than the parameter (first) from this set: 0, 1, 6, 8, 9.
findTotal is recursive as we should do the calculation for each digit.
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When considering a number like 9999, we ignore the permutations that start with 9. But, when we calculate the next digits, we are actually calculating the number of permutations that start with 9. Pretty clear now.
Co-authored-by: ErdemT09 <63192680+ErdemT09@users.noreply.github.com>
Co-authored-by: ErdemT09 <63192680+ErdemT09@users.noreply.github.com>
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It's a good method of problem solving to reduce a problem to another one. I like how that's being done here.
Approved.
Vielen Dank für die Codeüberprüfung und für deine wertvolle Zusammenarbeit. Ich rufe bewusst eine Methode in einer anderen Klasse auf, um ein Beispiel für unsere Idee des "Lego-Bausteine" zu geben. |
Resolves: #228
As we understand here: #156, if a number is generated using the numbers: 0, 1, 6, 8, 9 and :
if it does
not equalitself when it is rotated 180 degrees, it is aconfusing number.If it
equalsitself when it is rotated 180 degrees, it is astrobogrammatic number.Therefore:
It means, we can use the code here #323, and just subtract its output from the total count of all numbers generated using 0, 1, 6, 8, 9.