http://stackoverflow.com/questions/3963409/interview-question-dealing-with-m-occurrences-among-n
On Tue, Sep 13, 2011 at 1:48 PM, Gene <gene.ress...@gmail.com> wrote: > Here's a way: > > The base 2 xor operator has an obvious extension to base 3 such that > for all integers N, N ^ N ^ N = 0, just like the normal xor has N ^ > N = 0. > > This base 3 operator a^b just adds corresponding digit pairs of a and > b mod 3 to get the digits of the result. > > So the algorithm is to convert each input number to base 3 and tally > up the total with the base 3 ^ operator. The result will be the > answer in base 3. > > The example above in base 3 is > 2,1,11,12,1,11,2,2,11,1 > > Running total with ^: > > 0 ^ 2 = 2 > 2 ^ 1 = 0 > 0 ^ 11 = 11 > 11 ^ 12 = 20 > 20 ^ 1 = 21 > 21 ^ 11 = 2 > 2 ^ 2 = 1 > 1 ^ 2 = 0 > 0 ^ 11 = 11 > 11 ^ 1 = 12 > > And 12 is 5 base 3. > > The total will never have more digits than the biggest number. This > is O(1) space. You have to assume base 3 conversion is a constant > time operation, but this is pretty reasonable. > > If the problem changes to "all the numbers are repeated K times except > for one, which appears only once, you can do the same thing with base > K to get the answer. > > On Sep 11, 2:10 pm, Neha Singh <neha.ndelhi.1...@gmail.com> wrote: > > You are given an array that contains integers. The integers content is > such > > that every integer occurs 3 times in that array leaving one integer that > > appears only once. > > Fastest way to find that single integer > > eg: > > Input: [2,1,4,5,1,4,2,2,4,1] > > Answer: 5 > > > > The solution must be of O(n) time and O(1) space > > -- > You received this message because you are subscribed to the Google Groups > "Algorithm Geeks" group. > To post to this group, send email to algogeeks@googlegroups.com. > To unsubscribe from this group, send email to > algogeeks+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/algogeeks?hl=en. > > -- You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. To post to this group, send email to algogeeks@googlegroups.com. To unsubscribe from this group, send email to algogeeks+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/algogeeks?hl=en.
