@bhavana : Explain..!! as far as i get you is that it would be same as implementing map ...!! isn't ??
On Fri, May 27, 2011 at 2:16 PM, bhavana <[email protected]> wrote: > can be solved easily if the elements of the array lie in a limited range > which can b known beforehand...!! > > > On Fri, May 27, 2011 at 2:10 PM, Aakash Johari <[email protected]>wrote: > >> yes, you are right. map insertion takes O(log n) time. so if you know the >> upper bound of N, you can simply map the existence/non-existence of any >> particular element in an array. that will be in constant time (for query >> purposes) and O(n) time for preprocessing. >> >> >> On Fri, May 27, 2011 at 1:29 AM, sukhmeet singh >> <[email protected]>wrote: >> >>> @Dave nd @Akash can u explain a bit more.. I didn't get what u say.. >>> Inserting in a map takes O(log n) time !! >>> >>> On Fri, May 20, 2011 at 8:35 PM, Aakash Johari <[email protected]>wrote: >>> >>>> @Dave: This is what is still a doubt to me. I have searched but couldn't >>>> get the info regarding this. >>>> >>>> >>>> On Fri, May 20, 2011 at 8:01 AM, Dave <[email protected]> wrote: >>>> >>>>> @Aakash: And tell me how map works. Is making an entry O(1) regardless >>>>> of the value of the entry? For example, is it O(n) to map the sequence >>>>> 1, 4, 9, 16, 25, ..., n^2? >>>>> >>>>> Dave >>>>> >>>>> On May 20, 9:39 am, Aakash Johari <[email protected]> wrote: >>>>> > @Dave: I got you. I will have to check before pushing the element in >>>>> map. >>>>> > >>>>> > >>>>> > >>>>> > >>>>> > >>>>> > On Fri, May 20, 2011 at 7:30 AM, Dave <[email protected]> >>>>> wrote: >>>>> > > @Aakash: Yeah, but try the same array with sum = 6 and see what >>>>> > > happens. >>>>> > >>>>> > > Dave >>>>> > >>>>> > > On May 20, 9:04 am, Aakash Johari <[email protected]> wrote: >>>>> > > > int main() >>>>> > > > { >>>>> > > > int a[10] = {5, 3, 10, 9, 8, 23, 11, 4, 12, 6}; >>>>> > > > int i; >>>>> > > > int sum; >>>>> > > > int flag = 0; >>>>> > >>>>> > > > map<int, int> m; >>>>> > >>>>> > > > for ( i = 0; i < 10; i++ ) { >>>>> > > > m[a[i]] = 1; >>>>> > > > } >>>>> > >>>>> > > > sum = 13; >>>>> > >>>>> > > > for ( i = 0; i < 10; i++ ) { >>>>> > > > if ( m[sum - a[i]] == 1 ) { >>>>> > > > flag = 1; >>>>> > > > break; >>>>> > > > } >>>>> > > > } >>>>> > >>>>> > > > if ( flag == 1 ) >>>>> > > > cout << a[i] << " " << sum - a[i] << endl; >>>>> > >>>>> > > > return 0; >>>>> > >>>>> > > > } >>>>> > > > On Fri, May 20, 2011 at 7:01 AM, hari <[email protected]> >>>>> wrote: >>>>> > > > > We can sort using STL sort function in main() before function >>>>> call of >>>>> > > > > arraysum(). >>>>> > >>>>> > > > > On May 20, 6:49 am, Gunjan Sharma <[email protected]> >>>>> wrote: >>>>> > > > > > First of all there is an infinite loop in this code.... >>>>> > > > > > Secondly it works only for sorted array. >>>>> > >>>>> > > > > > On Fri, May 20, 2011 at 7:16 PM, hari <[email protected]> >>>>> wrote: >>>>> > > > > > > In while loop have i,j which points first and last index of >>>>> array. >>>>> > > In >>>>> > > > > > > while loop, Check the sum of a[i],a[j], If sum<k,increment >>>>> i or >>>>> > > else >>>>> > > > > > > decrement j. Run the while loop till i<j.. >>>>> > >>>>> > > > > > > CODE: >>>>> > >>>>> > > > > > > int arraysum(int a[], int k, int i, int j) >>>>> > > > > > > while(i<j) >>>>> > > > > > > { >>>>> > > > > > > int p=0; >>>>> > > > > > > int b[10]; //to store index of selected nos >>>>> > > > > > > sum=a[i]+a[j]; >>>>> > > > > > > if (sum==k) >>>>> > > > > > > { >>>>> > > > > > > b[p++]=i;b[p++]=j; >>>>> > > > > > > } >>>>> > > > > > > elseif(sum<k) >>>>> > > > > > > i++; >>>>> > > > > > > else(sum>k) >>>>> > > > > > > j++; >>>>> > > > > > > return b; >>>>> > > > > > > } >>>>> > >>>>> > > > > > > On May 20, 4:38 am, amit <[email protected]> wrote: >>>>> > > > > > > > given an array of integers, and an integer k, find out >>>>> two >>>>> > > elements >>>>> > > > > > > > from the array whose sum is k in O(n) time. if no such >>>>> element >>>>> > > exists >>>>> > > > > > > > output none. >>>>> > >>>>> > > > > > > -- >>>>> > > > > > > You received this message because you are subscribed to the >>>>> Google >>>>> > > > > Groups >>>>> > > > > > > "Algorithm Geeks" group. >>>>> > > > > > > To post to this group, send email to >>>>> [email protected]. >>>>> > > > > > > To unsubscribe from this group, send email to >>>>> > > > > > > [email protected]. >>>>> > > > > > > For more options, visit this group at >>>>> > > > > > >http://groups.google.com/group/algogeeks?hl=en. >>>>> > >>>>> > > > > > -- >>>>> > > > > > Regards >>>>> > > > > > Gunjan Sharma >>>>> > > > > > B.Tech IV year CSE >>>>> > >>>>> > > > > > Contact No- +91 9997767077 >>>>> > >>>>> > > > > -- >>>>> > > > > You received this message because you are subscribed to the >>>>> Google >>>>> > > Groups >>>>> > > > > "Algorithm Geeks" group. >>>>> > > > > To post to this group, send email to >>>>> [email protected]. >>>>> > > > > To unsubscribe from this group, send email to >>>>> > > > > [email protected]. >>>>> > > > > For more options, visit this group at >>>>> > > > >http://groups.google.com/group/algogeeks?hl=en. >>>>> > >>>>> > > > -- >>>>> > > > -Aakash Johari >>>>> > > > (IIIT Allahabad)- Hide quoted text - >>>>> > >>>>> > > > - Show quoted text - >>>>> > >>>>> > > -- >>>>> > > You received this message because you are subscribed to the Google >>>>> Groups >>>>> > > "Algorithm Geeks" group. >>>>> > > To post to this group, send email to [email protected]. >>>>> > > To unsubscribe from this group, send email to >>>>> > > [email protected]. >>>>> > > For more options, visit this group at >>>>> > >http://groups.google.com/group/algogeeks?hl=en. >>>>> > >>>>> > -- >>>>> > -Aakash Johari >>>>> > (IIIT Allahabad)- Hide quoted text - >>>>> > >>>>> > - Show quoted text - >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "Algorithm Geeks" group. >>>>> To post to this group, send email to [email protected]. >>>>> To unsubscribe from this group, send email to >>>>> [email protected]. >>>>> For more options, visit this group at >>>>> http://groups.google.com/group/algogeeks?hl=en. >>>>> >>>>> >>>> >>>> >>>> -- >>>> -Aakash Johari >>>> (IIIT Allahabad) >>>> >>>> >>>> >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "Algorithm Geeks" group. >>>> To post to this group, send email to [email protected]. >>>> To unsubscribe from this group, send email to >>>> [email protected]. >>>> 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 [email protected]. >>> To unsubscribe from this group, send email to >>> [email protected]. >>> For more options, visit this group at >>> http://groups.google.com/group/algogeeks?hl=en. >>> >> >> >> >> -- >> -Aakash Johari >> (IIIT Allahabad) >> >> >> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Algorithm Geeks" group. >> To post to this group, send email to [email protected]. >> To unsubscribe from this group, send email to >> [email protected]. >> 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 [email protected]. > To unsubscribe from this group, send email to > [email protected]. > 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. 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