Windows Vista Slow Login Problem

There are some programs registered at the startup, which makes the vista login very slow, about up to 3 mins, we need to removed them using msconfig.

msconfig -> services -> hide all microsoft services 

uncheck these if they exist: xaudio, vongo, stllsvr,roxmediad89, installdriver table manager, cyberlink background, cyberlink task, Flexnet Licensing Services

Then click on boot tab ->advanced options -> number of processors 2 -> maximum memory.

I went from 2 min to 15 seconds bootup doing this.

Also install TweakNow RegCleaner and remove all the unneccessary entries from the registry, it can also delete unneccessary temp files from the disk and also help in doing registry defragmentation. Its free and safe tool. It can be downloaded from here

You can also removed those entries related to them in the msconfig and services list using the below procedure.

How to Remove Entries From MSCONFIG Services

Startup programs provide users with an easy way to load programs automatically each time the computer boots. The programs that start each time Windows starts are listed in an application called MSCONFIG. Even after disabling the programs, they are still listed in the MSCONFIG application in case you decide to re-enable them. You can prevent these services from being listed by editing the Windows registry

1. Click the Windows Start button and select "Run". Enter "regedit" in the text box and click the "Ok" button. This opens the Windows registry editor.
2. Navigate to the "HKEY_LOCAL_MACHINE \ Software \ Microsoft \ Shared Tools \ MSConfig \" key in the registry. When you click the "MSConfig" key, a list of subkeys is displayed. One of these is the services key, which holds the values you want to remove.
3. Click a program name in the "Services" directory that you want to delete from startup. Press the "Delete" key on your keyboard. Select "Yes" at the confirmation screen. The service is removed from MS Config startup. Continue to do this with each service you want to remove from MSCONFIG.

How to removed the service from the service list

 

Normally it should not be necessary to manually delete a service. Uninstalling an application should remove its associated service (if any).

However, should it be necessary to manually remove a service:

1. Run Regedit or regedt32.
2. Fnd the registry entry:  HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Service
3. Find the service there and delete it

You may wish to look at the keys and see what files the service was using and perhaps delete them also.

Note:

• You will have to reboot before the list gets updated in server manager.
• I have had it pointed out that some programs are cunning and prevent you from removing their service easily. (For example the spyware\malware called ‘Command Service’ - "cmdService".) These change the permissions to make it more difficult for you to delete them. For these you will have to right click on the ‘service’ in regedit (regedt32), go to permissions and grant the administrator full control before the service can be deleted

Ant and Spider Problem

Given a cube. A ant is placed in a corner and cannot move. A spider starts from the opposite corner, and can move along cube edges in any direction (x,y,z) with probablity 1/3. What is the expected number of steps for this spider to get to the ant?

Let x represent the expected number of moves it takes to reach the ant when the spider is one move away (i.e., at any one of the three vertices of the cube adjacent to the ant). Let y represent the expected number of moves it takes to reach the ant when the spider is two moves away, and let z represent the expected number of moves it takes to reach the ant when the spider is three moves away (at the opposite vertex on the cube).

Then z = 1 + y, since after the first move, the spider will be one move away. From this point, there is a (2/3) chance that the spider will move to a vertex adjacent to the ant and there is a (1/3) chance he will move back to his starting position, Thus, y = 1 + (2/3)x + (1/3)z.

Similarly, x = 1 + (1/3)(0) + (2/3)(y). This system of 3 equations with 3 unknowns has solution z=10, y=9, and x=7. So, it will take 10 steps to reach the ant, on average, from the spider's initial position.

7 Bucket and Poison Problem

There are 7 buckets with water, and one of them is poisoned. You have infinite number of flies, and if you put a fly in poisonous bucket, it will take seven days to die. You need to send your friend a non-poisonous bucket in 1 week, and also you need to find out which bucket is poisoned. How many least number of flies you need to it? and how do you do it?

1) One answer would be, You need one fly for this.

How?  You put the fly in any one of the bucket, and if it dies in one week then it is the poisonous one, and send any one of the other 6 to your friend, and if fly does not die, then its non-poisonous, and you need to send this to your friend and since you have sent to your friend in one week, now take your time and repeat to find out which has the poison with the same fly.

2) Since first answer may be ridiculous, the second answer would be using 3 flies.

How? You need to number the buckets from 1 to 7 in binary and then assign one bit for each flies, and dip the fly in those buckets which has the corresponding bit set in the bucket number in binary, after seven days, if the fly dies consider it as 1 otherwise 0, and get the binary number for bucket which contains the poison.

Classic 25 Horse Problem

Classic 25 horse problem,
25 Horses,
Have a 5 horse track,
No stopwatch,
How many races are required to determine the 3 fastest horses?

Answer : 7 Races

And here goes why? 

1. we have 5 races for 25 horses that 5 horses on a team, define each team as a, b, c, d, e.
2. carry a best horse race for each team first place, define them as a.1,b.1,c.1,d.1,e.1
3. assume prior best horse race 's top 3 places are a.1 b.1 c.1 , so we know the fastest horse is a.1
4. we only need to take last race to know who are second and third quickest horse.
5. The horses that participate in this race are b.1 b.2 a.2 a.3 c.1 , this race 's top 2 places are 2nd and 3rd quickest horses

Search two numbers from array to make a sum

You have a array of random numbers and you are given a number k. Find the 2 elements in the array which sum up to k.

e.g: If my array is {2,5,3,1,8,7,5,4} and k=6.

Then 2 numbers that sum up to 6 are 5 and 1.

step 1: sort the array //O(n.log(n))

arr=2,5,3,1,8,7,5,4 --> 1,2,3,4,5,5,7,8

//size=8

step 2:

i=0, j=7

if a[i]+a[j]==K //done

if a[i]+a[j] > K //j--

if a[i]+a[j] < K //i++

repeat step2, till it reaches mid point //O(n)