#codingexercise
Given two sorted linked lists, find their intersection as a new list
For example 1,2,3,4,5,6 with 2,4,6,8 should result in 2,4,6
Node sortedIntersect(node a, node b)
{
Node dummy;
dummy.next = null;
Node tail = dummy;
While (a != null && b != null)
{
If(a.data ==b.data){
Copy(tail.next, a.data);
A=a.next;
B=b.next;
Tail = tail.next;
}else if (a.data < b.data){
a.=a.next;
}else{ b = b.next;}
}
Return dummy.next;
}

Cloudian Storage and s3 api example 

Most online documentation skip over the example of a programmatic access to Cloudian storage saying that what works for AWS works for Cloudian. It’s true that both support S3 api but there are some caveats. First, the key/secret pairs are not universal. Cloudian servers cut their own keys and do not make them available to others.  Second the direct REST API calls to the server do not appear to be straightforward as the AWS s3 3 documentation states. While it might be possible to capture the packets from tools such as s3cmd in order to dump the API calls made, the s3 sdks seem to work seamlessly. So here are some examples to show how to use them. 

First an example with a tool: 

Download the s3cmd tool  and modify the configuration file  with these values 

[default] 

access_key = your_access_key_goes_here 

host_base =  cloudianserver.com 

host_bucket = %(bucket)s.cloudianserver.com 

secret_key = your_secret_key_here 

website_endpoint = http://%(bucket)s.cloudianserver.com/ 

Then issue “s3cmd ls” to see the following kind of output: 

2016-06-24 17:55  s3://bucket1 

2016-06-24 17:55  s3://bucket2 

2016-04-22 17:32  s3://bucket3 

Second try the boto sdk: 

def listS3(): 

    import boto 

    import boto.s3 

    import sys 

    import os 

    import math 

    from boto.s3.key import Key 

    try: 

       from urllib.parse import quote_plus 

    except: 

       from urllib import quote_plus 

    try: 

       from ConfigParser import RawConfigParser 

    except: 

       from configparser import RawConfigParser 

    parser = RawConfigParser() 

    parser.read('config.ini') 

    Cloudian_ACCESS_KEY_ID = parser.get('Cloudian', 'key') 

    Cloudian_SECRET_ACCESS_KEY = parser.get('Cloudian', 'secret') 

    conn = boto.connect_s3( 

    aws_access_key_id= Cloudian_ACCESS_KEY_ID, 

    aws_secret_access_key = Cloudian_SECRET_ACCESS_KEY, 

    host = ‘cloudianserver.com') 

   bucket_name = 'bucket1' 

    bucket = conn.get_bucket(bucket_name, validate=False) 

    print('bucket_list='+repr(bucket.list())) 

    for item in bucket.list(): 

        print(repr(item)) 

listS3() 

This should give an output like following: 

<Key: bucket1,1424338922-Tulips.jpg> 

<Key: bucket1,1424344182-Hydrangeas.jpg> 

#data structure discussion : https://1drv.ms/w/s!Ashlm-Nw-wnWk1i1yfh79Kw_ki7O 

#codingexercise
Generate a 2D distance matrix for the nearest distance from each cell as city location to  a parking spot that appears as one or more occupied cells.

 static int[][] getParkingDistanceGrid(int cityLength, int cityWidth, int[] parkingXCoordinates, int[] parkingYCoordinates) {

        var d = new int[cityWidth][];

        for (int i = 0; i < cityWidth; i++)

            d[i] = new int[cityLength];

        for (int i = 0; i < cityWidth; i++)

        {

            for (int j = 0; j < cityLength; j++)

                {

                    var parkingdistances = new List<int>();

                    for (int count = 0; count < parkingXCoordinates.Length; count++)

                    {

                        int distance = GetDistance(i+1, j+1, parkingXCoordinates[count], parkingYCoordinates[count]);

                        parkingdistances.Add(distance);

                    }

                    int min = INT_MAX;

                    for (int k = 0; k < parkingXCoordinates.Length; k++)

                        if (parkingdistances[k] < min)

                           min  = parkingdistances[k];

                    d[i][j] = min; 

                }

        }

        return d;

    }

    static int GetDistance(int r1, int c1, int r2, int c2)

    {

        int deltax = r1 - r2;

        deltax = deltax > 0 ? deltax : 0-deltax;

        int deltay = c1 - c2;

        deltay = deltay > 0 ? deltay : 0-deltay;

        return deltax + deltay;        

    }

Generate a recommendation list of courses taken by the social circle of a user. The recommendation must include courses taken by the members of her social circle but not by her. It must be ranked by the number of attendees to the course. A social circle consists only of the persons direct friends and their direct friends.

public List<string> getRankedCourses(string user) {

    var coursePopularity = new Dictionary<string, int>();

    var circle = new List<string>();

    

    var direct = getDirectFriendsForUser(user);

    circle.AddRange(direct);

    foreach (var friend in direct){

        if (friend != user){

        var directForFriend = getDirectFriendsForUser(friend);

        directForFriend.Remove(user);

        circle.AddRange(directForFriend);

        }

    }

    

    foreach (var person in circle)

    {

        var attended = getAttendedCoursesForUser(person);

        foreach(var course in attended)

        {

            if (!coursePopularity.ContainsKey(course))

            {

                coursePopularity.Add(course,1);   

            }

            else

            {

                coursePopularity[course] += 1;   

            }

        }

    }

    

    foreach(var attending in getAttendedCoursesForUser(user))

    {

     coursePopularity.Remove(attending);   

    }

    List<KeyValuePair<string, int>> ranked = coursePopularity.ToList();

    ranked.Sort(

    delegate(KeyValuePair<string, int> pair1,

    KeyValuePair<string, int> pair2)

    {

        return pair1.Value.CompareTo(pair2.Value);

    }

    );

    

    var recommendations = new List<string>();

    foreach (var kvp in ranked)

        recommendations.Add(kvp.Key);

    recommendations.Reverse();

    return recommendations;

}

#codingexercise

test whether an integer is BigIndian or LittleIndian
bool IsLittleIndian()
{
int c = 1;
char * ptr = reinterpret_cast<char*>&c;
return *ptr & 0x1;
}