Shantibhushan Naik

Tag: friends

  • Farewell 2012 and welcome 2013

    We had a nice time with one on my old friends – Yogesh, and his family. Enjoyed a memorable time with his daughter Yukta, and enjoyed delicious ‘parathas’ by his wife Hema. After a hearty chat, we bid farewell to 2012 over a sumptuous Indian dinner at Swagat, Roppongi.

  • Maintaining relationship – common friends

    I was posed a very trivial question from one of my friends recently. It picked my interest, since I could not readily solve it, and I had the inkling that there is a better, simple solution for this problem.

    The problem was, let’s say I have a table of users as below
    User's table data

    And these users have friends as below

    User's friends data or more easier to read as User's friends data

    Now, the trivial task was find common friends for users 1, and 5, hence naturally the answer should be

    User 1 : Woody’s friends, and User 5 : Andy’s friends  are

    Woody's friends and Andy's friends

    So, the question I had was what could be the best SQL query that would be return me this result?

    Woody and Andy's common friends

    I thought of 2 different SQL queries

    SELECT f.fid, u.name 'Woody and Andy\'s common friends' FROM
    (SELECT f.`fid` FROM friends f
    WHERE f.`uid` IN (1,5)
    GROUP BY f.`fid` HAVING COUNT(f.`fid`) > 1) f INNER JOIN user u ON (u.uid=f.fid)

    -or- another one was

    SELECT f.fid, u.name 'Woody and Andy\'s common friends' FROM
    (SELECT a.fid FROM
    (SELECT * FROM friends f
    WHERE f.`uid`=1) a INNER JOIN
    (SELECT * FROM friends f
    WHERE f.`uid`=5) b ON (a.fid=b.fid)) f INNER JOIN user u ON (u.uid=f.fid)

    Both seem to work, but is there any elegant way of getting common friends in a much simpler SQL query? At this moment, I logically find first SQL query more intuitive since all it does is pickup friends who appear more than once when users are 1 and 5. The second SQL query seems plain brute force approach.

  • Merging pre-sorted lists

    A while ago, I came across an interesting problem. We have 3 different sorted queues (entries were sorted by time), out of which we had to pickup the smallest time, and send the first arrived entry out of those 3 queues in sequence.

    Q1 Q2 Q3
    2 3 1
    5 4 6
    7 6 9
    8 10 11

    As you can see, all queues (Q1, Q2, Q3) are already sorted, but on application side we have to pickup entries across all queues in sorted order and process them. So the entries should be processed in 1, 2, 3, 4, 5, … 11 sequence. Frankly this is merging of already sorted lists, and a person from computer science background should already know this. But I don’t come from such background, and the solution one of my friends gave was plain amazing.

    The solution was pickup first entry from each queue, compare them, choose the smallest and process it first.

    Q1 Q2 Q3 Smallest
    2 3 1 1

    Thus, here 1 is processed first. Now pickup next entry from queue where smallest was found (Q3 in this example), so now the next comparison becomes like this

    Q1 Q2 Q3 Smallest
    2 3 6 2

    The smallest is 2, so this is processed and next entry from Q1 was picked-up

    Q1 Q2 Q3 Smallest
    5 3 6 3

    And so on… giving us

    Q1 Q2 Q3 Smallest
    2 3 1 1
    2 3 6 2
    5 3 6 3
    5 4 6 4
    5 6 6 5
    7 6 6 6
    7 10 6 6
    7 10 9 7
    8 10 9 8
    10 9 9
    10 11 10
    11 11

    A simple, and elegant solution, isn’t it? Is there any other better alternative?

  • Visit to Mahesh’s place in Nishi-kasai

    We had a splendid day today! We were invited to Mahesh’s place in Nishi-kasai. Amrita, Nicolas enjoyed their playtime with little Vibha.

    We feasted on an extremely delicious lunch prepared by Rajshri (Mahesh’s wife) – Puran Poli, with Amti. And not to mention, how tasty the Bhaji was… ahaha yummy!

    The next was a well mixed dish of basmati rice with amti, one cannot describe it’s taste in words unless you eat it prepared from Rajshri’s hands once.

    All of us really enjoyed the short visit to our friends, and we could really say our visit as greatly satisfying (and appetizing) despite of the gloomy, rainy day outside.

    Some very funny moments, especially when Amrita, Nicolas decided to play with Mahesh, and Rajshri.

    We do wish to visit our friend often, and see how Amrita, Vibha’s new friendship grows deeper. Nicolas with his unsatisfied appetite, was eating anything that came in the way of his mouth. Hope he doesn’t upset his stomach with this cocktail of apple juice, bhaji, snacks, rice, puran poli, milk, and vitamin water (phew!)