[algogeeks] Re: Finding a single repeated element in an array

2007-08-24 Thread L7
> Your solution really parses terms on what it means to be performing > asymptotic analysis... you cannot say that this storage is constant in > 32 bits, when it is not said that you are using 32 bit numbers. If you > are speaking asymptotically at all, saying that something is O(n) or > O(log(n)

[algogeeks] Re: Finding a single repeated element in an array

2007-08-24 Thread L7
> so, does 135,000,000 distinct integers work for any size of input? Always (notice my stipulation of 32 bit). However, regardless of the size of an integer (in bits) there is _always_ a fixed number of bits that can represent it in the manner I explained. > (Nowhere in the original problem did

[algogeeks] Re: Finding a single repeated element in an array

2007-08-24 Thread wbspresslyjr
I personally would agree that there is probably not a solution. If you really wanted to stick with the constant space -- you are probably stuck with the O(n^2) algorithm. I do not think there is probably a solution in O(nlog(n)) in constant space either... I will see if I can find a bound to tie i

[algogeeks] Re: Finding a single repeated element in an array

2007-08-24 Thread wbspresslyjr
"That number wont ever change. Regardless if you have 2 numbers or 257 numbers in your array. If you scale that to 32 bit numbers, you get the following requirement ~ 135,000,000 distinct integers. It is a large requirement, but it is constant and capable of determining what you want regardless i

[algogeeks] Re: Finding a single repeated element in an array

2007-08-24 Thread L7
On Aug 24, 10:19 pm, wbspresslyjr <[EMAIL PROTECTED]> wrote: > On Aug 21, 10:13 pm, L7 <[EMAIL PROTECTED]> wrote: > > > Sorry. I wrote too quickly. The amount you need is not determined by > > log, but by division. > > For the sake of argument, say you could hold the value 0 - 255. This > > mean

[algogeeks] Re: Finding a single repeated element in an array

2007-08-24 Thread wbspresslyjr
On Aug 21, 10:13 pm, L7 <[EMAIL PROTECTED]> wrote: > Sorry. I wrote too quickly. The amount you need is not determined by > log, but by division. > For the sake of argument, say you could hold the value 0 - 255. This > means we are dealing with 8-bit storage, but it makes the example > easier. Yo

[algogeeks] Re: Finding a single repeated element in an array

2007-08-24 Thread wbspresslyjr
Oops -- sorry, I have been working on that problem lately... I guess I didn't see that the problem you were working on was different -- Cheers, W On Aug 24, 5:46 pm, L7 <[EMAIL PROTECTED]> wrote: > On Aug 24, 1:00 am, wbspresslyjr <[EMAIL PROTECTED]> wrote: > > > I've heard this problem stated a

[algogeeks] Re: Find largest sum

2007-08-24 Thread Lego Haryanto
I should take my statement regarding the O(n) space for DP back ... If we don't care storing each intermediate result, ... then space is also O(1). On 8/24/07, Lego Haryanto <[EMAIL PROTECTED]> wrote: > > For the DP recurrence, consider f(i) is the "best contiguous sum ending at > this index i".

[algogeeks] Re: Finding a single repeated element in an array

2007-08-24 Thread L7
On Aug 24, 2:11 am, wbspresslyjr <[EMAIL PROTECTED]> wrote: > Oops -- for approach 1. down here, I meant to say that the hash table > breaks the constant space requirement... I guess I got ahead of Depends on how you implement the hash. See above for a perfectly constant-size hash approach. -

[algogeeks] Re: Finding a single repeated element in an array

2007-08-24 Thread L7
On Aug 24, 1:00 am, wbspresslyjr <[EMAIL PROTECTED]> wrote: > I've heard this problem stated as such: assume you have an array of N > numbers, each ranging on the interval [1,N-1], only one of these > elements repeating in Read-Only memory. You only have O(1) (constant) > "scratch" space to work

[algogeeks] Patents for Electromagnetics and Bioma nipulation

2007-08-24 Thread soleilmavis
Patents for Electromagnetics and Bioma nipulation http://soleilmavis.spaces.live.com/blog/cns!9B6CD1D7F6F8F411!2177.entry --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups "Algorithm Geeks" group. To post to this grou

[algogeeks] Re: Find largest sum

2007-08-24 Thread Lego Haryanto
For the DP recurrence, consider f(i) is the "best contiguous sum ending at this index i". f(i) = a[i], if i == 0 f(i) = max(a[i], f(i-1)+a[i]), on other cases Basically, for each index i, to end a subarray ending at i, it's obvious that we can either "extend" the best solution for previous index,

[algogeeks] Re: Find largest sum

2007-08-24 Thread Lego Haryanto
I thought I already answered earlier even thought it's just words and no code. sum = 0 best = -INF FOREACH val IN a DO sum = sum + val best = MAX(best, sum) IF sum < 0 THEN sum = 0; ENDFOR O(n) runtime, O(1) space. DP can be done as well in O(n), but due to the nature of DP, you'll n

[algogeeks] Re: Fastest known implementation and algorithm for the shortest path

2007-08-24 Thread Muntasir Azam Khan
For all pairs shortest paths you could use Floyd Warshall. For single source shortest paths, you can use Dijkstra's Algorithm, or even Bellman Ford algorithm if negative cost cycles are allowed. - Original Message - From: "TheTravellingSalesman" <[EMAIL PROTECTED]> To: "Algorithm Geeks"

[algogeeks] Re: Algo to get GCD of given numbers

2007-08-24 Thread Albert Sanchez
int gcd(int a, int b) { return (b==0 ? a : gcd(b,a%b)); } http://en.wikipedia.org/wiki/Euclidean_algorithm On 8/17/07, Muntasir Azam Khan <[EMAIL PROTECTED]> wrote: > > > On Aug 17, 6:53 pm, anshu <[EMAIL PROTECTED]> wrote: > > Do you think sorting would help here? > > I mean, arranging the numbe

[algogeeks] Re: Finding a single repeated element in an array

2007-08-24 Thread Peeyush Bishnoi
Everyone , I have posted the solution for this problem in O(n) also with O(nlogn) . Just check my previous mails in this loop mail. --- Peeyush Bishnoi On 8/16/07, Chonku <[EMAIL PROTECTED]> wrote: > > I think the only faster way I know off is by using a hashset which uses > O(nlog(n/m)) time but

[algogeeks] Re: Find largest sum

2007-08-24 Thread Albert Sanchez
what is the DP recurrence? On 8/23/07, ilija <[EMAIL PROTECTED]> wrote: > > > If the subarray needs to be continuous, then you can do it using DP. > If it doesn't, you can do it using an O(n) algo - simply sum all the > positive integers. > > On 22 kol, 19:55, Ravi <[EMAIL PROTECTED]> wrote: > > Y

[algogeeks] Re: Finding a single repeated element in an array

2007-08-24 Thread Chonku
I think the only faster way I know off is by using a hashset which uses O(nlog(n/m)) time but the value comes out to be numerically closer to O(nlogn). On 8/16/07, dsha <[EMAIL PROTECTED]> wrote: > > Hi there, > > I'm interested in the following problem: there is an array of integers > that conta

[algogeeks] Re: Finding a single repeated element in an array

2007-08-24 Thread TheTravellingSalesman
Amazing, I love your solution. Good call Vaibhav On Aug 17, 12:51 am, "Vaibhav Jain" <[EMAIL PROTECTED]> wrote: > if u know the range of values stored in array then > let me assume values 1 to k then u can calculate sum of numbers stored in > array in O(n) complexity. > after that apply formul

[algogeeks] Post order traversal of a binary tree without recursion

2007-08-24 Thread Phani Kumar Ch. V.
Hi all, Please let me know if this pseudo code gives correct solution for iterative post-order traversal of a binary tree. void postOrderTraversal(Tree *root) { node * previous = null; node * s = null; push(root); while( stack is not empty ) {

[algogeeks] Re: graph theory

2007-08-24 Thread TheTravellingSalesman
Since it s a DAG, just multiply all the edge weights by -1. Then use dijkstra's to find the min shortest path. Wether some of the edge weights are negative or not, it shouldn't effect the solution as when using dijkstra's, we take the min node potentials. ,--- This can be proven On Aug

[algogeeks] Fastest known implementation and algorithm for the shortest path

2007-08-24 Thread TheTravellingSalesman
I'm trying to implement this in java. Given N nodes and M arcs, whats the fastest known implementation for the shortest path. I'm currently making use of the jgrapht library for java. The link is given below. http://jgrapht.sourceforge.net/ Any suggestion will be much appreciated. --~--~

[algogeeks] Re: Finding a single repeated element in an array

2007-08-24 Thread pradeep reguri
can u please how to find in o(n* log n)? On 8/16/07, dsha <[EMAIL PROTECTED]> wrote: > > > Hi there, > > I'm interested in the following problem: there is an array of integers > that contains each element only once except for one element that > occurs exactly twice. Is there a way to find this

[algogeeks] Post order traversal of a binary tree without recursion

2007-08-24 Thread Phani Kumar Ch. V.
Hi all, Please let me know if this pseudo code solution is correct for iterative post-order traversal of a binary tree. void postOrderTraversal(Tree *root) { node * previous = null; node * s = null; push(root); while( stack is not empty ) { s

[algogeeks] Re: Find largest sum

2007-08-24 Thread ilija
I would like to see your code for the first case. I really doubt that there exists an O(n) algo for this. On 23 kol, 16:11, "Lego Haryanto" <[EMAIL PROTECTED]> wrote: > Either case is O(n), in fact. > > On 8/23/07, ilija <[EMAIL PROTECTED]> wrote: > > > > > If the subarray needs to be continuous,

[algogeeks] Re: Finding a single repeated element in an array

2007-08-24 Thread wbspresslyjr
adding the numbers together is not constant space! that is logarithmic space! As in log base 2 of N bits to represent the number... Thus, as n grows large, your storage to hold the sum of the numbers is growing logarithmically in the number of bits per element... Not to mention that if the number

[algogeeks] Re: Finding a single repeated element in an array

2007-08-24 Thread wbspresslyjr
Here is the solution in PERL (this takes an Integer arg for the size of the list of numbers, and outputs the list, the walks through the lists, and the single repeating element) : #!/usr/bin/perl # setup problem -- this will embed the numbers 1...(N-1) into cells 1...N with one duplicate # first