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  • Fuzzy match two hash tables?

    - by alex
    Hi, I'm looking for ideas on how to best match two hash tables containing string key/value pairs. Here's the actual problem I'm facing: I have structured data coming in which is imported into the database. I need to UPDATE records which are already in the DB, however, it's possible that ANY value in the source can change, therefore I don't have a reliable ID. I'm thinking of fuzzy matching two rows, source and DB and make an "educated" guess if it should be updated and inserted. Any ideas would be greatly appreciated.

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  • What is better, a STL list or a STL Map for 20 entries, considering order of insertion is as importa

    - by Abhijeet
    I have the following scenario.The implementation is required for a real time application. 1)I need to store at max 20 entries in a container(STL Map, STL List etc). 2)If a new entry comes and 20 entries are already present i have to overwrite the oldest entry with the new entry. Considering point 2, i feel if the container is full (Max 20 entries) 'list' is the best bet as i can always remove the first entry in the list and add the new one at last (push_back). However, search won't be as efficient. For only 20 entries, does it really make a big difference in terms of searching efficiency if i use a list in place of a map? Also considering the cost of insertion in map i feel i should go for a list? Could you please tell what is a better bet for me ?

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  • Pool Billiard AI

    - by Sebi
    Im implementing a pool billiard game in Java and it all works fine. It is a multiplayer game, but nevertheless, it should also be possible to play it alone. For this purpose I'm trying to implement a simple KI. At the moment, the KI choose just randomly a direction and a random intensity of the impulse (don't know the correct english word for that). Of course this AI is very poor and unlikely to ever challenge a player. So i thought about improving the KI, but there are several hard to solve problems. First I thought of just choosing the nearest ball and to try to put it directly into the nearest hole. This isn't that bad, but if there other balls in the line between, it isn't really working anymore. Additionally this dosn't solve te problem of calculating the intensity of the impulse. So are there any general advice? Or any ideas? Best practices?

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  • Rotate array clockwise

    - by user69514
    I have a two dimensional array that I need to rotate 90 degrees clockwise, however I keep getting arrayindexoutofbounds... public int[][] rorateArray(int[][] arr){ //first change the dimensions vertical length for horizontal length //and viceversa int[][] newArray = new int[arr[0].length][arr.length]; //invert values 90 degrees clockwise by starting from button of //array to top and from left to right int ii = 0; int jj = 0; for(int i=0; i<arr[0].length; i++){ for(int j=arr.length-1; j>=0; j--){ newArray[ii][jj] = arr[i][j]; jj++; } ii++; } return newArray; }

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  • Query optimization (OR based)

    - by john194
    I have googled but I can't find answers for these questions. Your advice is appreciated. centOS on vps with 512MB RAM, nginx, php5 (fastcgi), mysql5 (myisam, not innodb). I need to optimize this app created by some ex-employee. This app is working, but it's slow. Table: t1(id[bigint(20)],c1[mediumtext],c2[mediumtext],c3[mediumtext],c4[mediumtext]) id is some random big number, and is PK Those mediumtext rows look like this: c1="|box-002877|" c2="|ct-2348|rd-11124854|hw-3949|wd-8872|hw-119037736|...etc.. " c3="|fg-2448|wd-11172|hw-1656|...etc.. " c4="|hg-2448|qd-16667|...etc." (some columns contain a lot of data, around 900 KiB, database around 300 MiB) Yes, mediumtext "is bad", and (20) is too big... but I didn't create this. Those codes can be found on any of those 4 mediumtext's... //he needs all the columns of the row containing $code, so he wrote this: function f1($code) { SELECT * FROM t1 WHERE c1 LIKE '%$code%' OR c2 LIKE '%$code%' OR c3 LIKE '%$code%' OR c4 LIKE '%$code%'; Questions: Q1. If $code is found on c1... mysql automatically stops checking and returns row=id+c1+c2+c3+c4? or it will continue (wasting time) checking c2, c3 and c4?... Q2. Mysql is working with this table on disk (not RAM) because of the mediumtext, right? is this the primary cause of slowness? Q3. That query can be cached by mysql (if using a big query_cache_size=128M value on the my.cnf)? or that's not cacheable due to the mediumtexts, or due to the "OR LIKE"...? Q4. Do you recommend rewriting this with mysql's INSTR() / LOCATE() / MATCH..AGAINST [FULLTEXT]?

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  • Next month, same day in PHP

    - by Guillermo
    I got a last time (and urgent) requeriment of an "event" that needs to be scheduled the same day of every month. Say of you set the start date on the 1st May you should get the next events on the 1st of Jun, 1 Jul etc. The problem comes with a start date on the 31st (the next ones could be 30 or 28 depending on the month) Considering that there are months with different numbers of days (28,30,31) depending on the month itself and the year... what would ba an easy way to setup this? Consider the following (and flawed) nextmonth function: $events = array() function nextmonth($date) { return $date+(60*60*24*30); } $curr = $start; while($curr < $end) { $events[ = $curr; $curr = nextmonth($curr); } Edited to add: The problem for me is, simply enought, is to solve what the number of days of any given month is and thus get the next corresponding date..

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  • Find all substrings of a string - StringIndexOutOfBoundsException

    - by nazar_art
    I created class Word. Word has a constructor that takes a string argument and one method getSubstrings which returns a String containing all substring of word, sorted by length. For example, if the user provides the input "rum", the method returns a string that will print like this: r u m ru um rum I want to concatenate the substrings in a String, separating them with a newline ("\n"). Then return the string. Code: public class Word { String word; public Word(String word) { this.word = word; } /** * Gets all the substrings of this Word. * @return all substrings of this Word separated by newline */ public String getSubstrings() { String str = ""; int i, j; for (i = 0; i < word.length(); i++) { for (j = 0; j < word.length(); j++) { str = word.substring(i, i + j); str += "\n"; } } return str; } But it throws exception: java.lang.StringIndexOutOfBoundsException: String index out of range: -1 at java.lang.String.substring(String.java:1911) I stuck at this point. Maybe, you have other suggestions according this method signature public String getSubstrings(). How to solve this issue?

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  • .NET Geometry Library

    - by dewald
    Does anyone know of a good (efficient, nice API, etc.) geometry open source library for .NET? Some of the operations needed: Data Structures Vectors (2D and 3D with floats and doubles) Lines (2D and 3D) Rectangles / Squares / Cubes / Boxes Spheres / Circles N-Sided Polygon Matrices (floats and doubles) Algorithms Intersection calculations Area / Volume calculations

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  • Why is my logic not working correctly for SPOJ TOPOSORT?

    - by Kavish Dwivedi
    The given problem is http://www.spoj.com/problems/TOPOSORT/ The output format is particularly important as : Print "Sandro fails." if Sandro cannot complete all his duties on the list. If there is a solution print the correct ordering, the jobs to be done separated by a whitespace. If there are multiple solutions print the one, whose first number is smallest, if there are still multiple solutions, print the one whose second number is smallest, and so on. What I am doing is simply doing dfs by reversing the edges i.e if job A finishes before job B, there is a directed edge from B to A . I am maintaining the order by sorting the adjacency list I created and storing the nodes which don't have any constraints separately so as to print them later in correct order . There are two flag arrays used , one for marking discovered node and one for marking the node whose all neighbors have been explored. Now my solution is http://www.ideone.com/QCUmKY (the important function is the visit funtion ) and its giving WA after running correct for 10 cases so its really hard to figure out where am I doing it wrong since it runs for all of the test cases which I have done by hand.

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  • Millions of 3D points: How to find the 10 of them closest to a given point?

    - by Kazoom
    A point in 3-d is defined by (x,y,z). Distance d between any two points (X,Y,Z) and (x,y,z) is d= Sqrt[(X-x)^2 + (Y-y)^2 + (Z-z)^2]. Now there are a million entries in a file, each entry is some point in space, in no specific order. Given any point (a,b,c) find the nearest 10 points to it. How would you store the million points and how would you retrieve those 10 points from that data structure.

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  • millions of 3d points how to 10 closest to origin

    - by Kazoom
    A point in 3-d is defined by (x,y,z). Distance d between any two points (X,Y,Z) and (x,y,z) is d= Sqrt[(X-x)^2 + (Y-y)^2 + (Z-z)^2]. Now there are a million entries in a file, each entry is some point in space, in no specific order. Given any point (a,b,c) find the nearest 10 points to it. How would you store the million points and how would you retrieve those 10 points from that data structure.

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  • Formula needed: Sort array to array-"snaked"

    - by aw
    After the you guys helped me out so gracefully last time, here is another tricky array sorter for you. I have the following array: a = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16] I use it for some visual stuff and render it like this: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Now I want to sort the array to have a "snake" later: // rearrange the array according to this schema 1 2 3 4 12 13 14 5 11 16 15 6 10 9 8 7 // the original array should look like this a = [1,2,3,4,12,13,14,5,11,16,15,6,10,9,8,7] Now I'm looking for a smart formula / smart loop to do that ticker = 0; rows = 4; // can be n cols = 4; // can be n originalArray = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]; newArray = []; while(ticker < originalArray.length) { //do the magic here ticker++; } Thanks again for the help.

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  • Most efficent way to create all possible combinations of four lists in Python?

    - by Baresi
    I have four different lists. headers, descriptions, short_descriptions and misc. I want to combine these into all the possible ways to print out: header\n description\n short_description\n misc like if i had (i'm skipping short_description and misc in this example for obvious reasons) headers = ['Hello there', 'Hi there!'] description = ['I like pie', 'Ho ho ho'] ... I want it to print out like: Hello there I like pie ... Hello there Ho ho ho ... Hi there! I like pie ... Hi there! Ho ho ho ... What would you say is the best/cleanest/most efficent way to do this? Is for-nesting the only way to go?

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  • Substring and its reverse in a string

    - by christa
    My professor was talking about this in a Dynamic programming class and asked us to think over it. She gave us some examples as well. Given a string, we were to find the longest continuous subsequence whose reverse is also a subsequence present in the given string. Example: INPUT: pqrstuvtsrv OUTPUT: i=3, k=2 rst -> tsr (rst found first at i=3 and for 2 more positions) INPUT: mpqrsrqp OUTPUT: i=2, k=6 pqrsrqp in reverse INPUT: mmpqssss OUTPUT: i=5, k=3 I thought of putting the string and its reverse into 2 different arrays and comparing character by character. But I'm sure this is not the best way to do it. Any suggestions as to what could be the most efficient ?

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  • SQL model optimization question

    - by supermogx
    I need to keep track of number of "hits" on a particular item in a DB. The thing is that the "hits" should stay unique with a user ID, so if a user hits the item 3 times, it should still count for a hit of 1. Also, I need to display the total number of hits for a particular item. Is there a better way than to store each hits for each items by each users in a separate table? Would keeping the user ID in a string separated by commas a better and efficient way?

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  • integer division properties

    - by aaa
    hi. does the following integer arithmetic property hold? (m/n)/l == m/(n*l) At first I thought I knew answer (does not hold), but now am not sure. Does it hold for all numbers or only for certain conditions, i.e. n > l?

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  • Number Random Shuffle

    - by stjowa
    Hi, I need a Javascript random number shuffler for my website. Seems simple, but I can not figure out how to do it. Can anyone help me out? I have the following array of numbers: 1 2 3 4 5 6 7 8 9 I would like to be able to have these numbers shuffled randomly. Like the following: 3 6 4 2 9 5 1 8 7 or 4 1 7 3 5 9 2 6 8 So, specifically, I would like a function that takes in an array of numbers (1 - n) and then returns that same array of numbers - shuffled randomly with different calls to the function. Maybe a noob function, but can't seem to figure it out. Thanks! NOTE: Thanks for the clarification on "Shuffle". Have found a lot more online about this with that term.

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  • How to detect a Triangle gesture with kinect?

    - by Akhilesh Mishra
    I am trying to implement a gesture recognition system which interprets the geometric gestures user makes and draws it on screen, I have some idea of how circle can be recognized, however i have no clue how to get started with triangle recognition. the data I have is X and Y coordinates of all points the gesture passed through. I get this data by tracking right hand. I found something online called Hough Transform , which is used for detecting lines but i am not sure whether it will work for discrete collection of points, Any ideas folks?

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  • Calculate shortest path through a grocery store

    - by Bart
    Hi, I'm trying to find a way to find the shortest path through a grocery store, visiting a list of locations (shopping list). The path should start at a specified startposition and can end at multiple endpositions (there are multiple checkout counters). Also, I have some predefined constraints on the path, such as "item x on the shopping list needs to be the last, second last, or third last item on the path". There is a function that will return true or false for a given path. Finally, this needs to be calculated with limited cpu power (on a smartphone) and within a second or so. If this isn't possible, then an approximation to the optimal path is also ok. Is this possible? So far I think I need to start by calculating the distance between every item on the list using something like A* or Dijkstra's. After that, should I treat it like the travelling salesman problem? Because in my problem there is a specified startnode, specified endnodes, and some constraints, which are not in the travelling salesman problem. Any help would be appreciated :)

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