first problem can be solved using a fixed sized array if we know the range of numbers or a hash table with an appropriate hash function and it is O(N) for time and space as some solutions above already mentioned this.
for the second problem, I don't think heap is the right data structure which is only good for getting min(max) element in logN time. A possible solution would be to use a combination of linked list and a hash table. For every incoming number num(i) of the stream, check if the number exists in the hash table and: 1. if it does not exist, add an entry in hash table and insert a node in linked list. HashTbl row is <key,val> pair of <num,Node*> where Node* points to the corresponding node entry in the linked list. linked list node should contain pointer(index) to the corresponding HashTblRow. It is like hash table entry pointing to corresponding node in the list and list node pointing to hash table entry.O(1) adding to hash table and list. 2. if it does exist, delete the node from hash table and find the list node address, and delete it from the list. O(1) operation To find the k-th unique number: just walk the list, O(k) On Thu, Feb 7, 2013 at 11:16 PM, bharat b <bagana.bharatku...@gmail.com> wrote: > @sourabh : how do u find whether the element in stream gets repeated in > heap.--> O(n) time...totally its O(nk) algo .. > > If we maintain max-heap with BST property on index, then it would be > O(nlogk). > > > On Wed, Feb 6, 2013 at 12:25 PM, sourabh jain <wsour...@gmail.com> wrote: >> >> for 2nd question you can make a heap with their index as a factor to >> heapify them. whenever a integer in stream gets repeated you just nead to >> remove it from heap and heapify it. >> >> >> On Wed, Feb 6, 2013 at 10:00 AM, navneet singh gaur >> <navneet.singhg...@gmail.com> wrote: >>> >>> nice algo ankit, so it will be nlogn using O (n) space only. What abt >>> 2nd Q., which have a big online stream. >>> >>> On Mon, Feb 4, 2013 at 9:30 PM, kumar ankit <k.anki...@gmail.com> wrote: >>> > For 1: >>> > i think you can use sorting, sort the array and keep the indices of the >>> > numbers in the sorted list. >>> > Now traverse the sorted list and in the sorted list you need to find >>> > the >>> > unique number with the >>> > minimum index which is easy to find. >>> > >>> > Eg: Array: 5 3 1 2 4 1 4 >>> > Indices: 0 1 2 3 4 5 6 >>> > >>> > >>> > After sorting : Array: 1 1 2 3 4 4 5 >>> > Indices: 2 5 3 1 4 6 1 >>> > >>> > Now you can see the unique number with lowest index is 3(index=1). So , >>> > you >>> > have your answer. >>> > >>> > >>> > On Mon, Feb 4, 2013 at 3:45 PM, navneet singh gaur >>> > <navneet.singhg...@gmail.com> wrote: >>> >> >>> >> 1. Given a array,find a first unique integer. >>> >> 2. Integers are coming as online stream,have to find a kth unique >>> >> integer >>> >> till now. >>> >> >>> >> For 1. >>> >> >>> >> Even we cannot use sorting for solving this as if we sort it than our >>> >> first number which is non-repetitive changes. >>> >> >>> >> The best I am able to do is nlogn using a space of O( n ). >>> >> >>> >> For 2. No idea >>> >> >>> >> -- >>> >> You received this message because you are subscribed to the Google >>> >> Groups >>> >> "Algorithm Geeks" group. >>> >> To unsubscribe from this group and stop receiving emails from it, send >>> >> an >>> >> email to algogeeks+unsubscr...@googlegroups.com. >>> >> For more options, visit https://groups.google.com/groups/opt_out. >>> >> >>> >> >>> > >>> > >>> > >>> > >>> > -- >>> > Kumar Ankit >>> > Senior Undergraduate >>> > Department of Computer Engineering >>> > Institute of Technology >>> > Banaras Hindu University >>> > Varanasi >>> > Ph: +91 9473629892 >>> > >>> > -- >>> > You received this message because you are subscribed to the Google >>> > Groups >>> > "Algorithm Geeks" group. >>> > To unsubscribe from this group and stop receiving emails from it, send >>> > an >>> > email to algogeeks+unsubscr...@googlegroups.com. >>> > For more options, visit https://groups.google.com/groups/opt_out. >>> > >>> > >>> >>> >>> >>> -- >>> navneet singh gaur >>> >>> -- >>> You received this message because you are subscribed to the Google Groups >>> "Algorithm Geeks" group. >>> To unsubscribe from this group and stop receiving emails from it, send an >>> email to algogeeks+unsubscr...@googlegroups.com. >>> For more options, visit https://groups.google.com/groups/opt_out. >>> >>> >> >> >> >> -- >> Regards, >> Sourabh Kumar Jain >> +91-8971547841 >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Algorithm Geeks" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to algogeeks+unsubscr...@googlegroups.com. >> For more options, visit https://groups.google.com/groups/opt_out. >> >> > > > -- > You received this message because you are subscribed to the Google Groups > "Algorithm Geeks" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to algogeeks+unsubscr...@googlegroups.com. > For more options, visit https://groups.google.com/groups/opt_out. > > -- You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. 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