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  • Why is it impossible to produce truly random numbers?

    - by Vinoth Kumar
    I was trying to solve a hobby problem that required generating a million random numbers. But I quickly realized, it is becoming difficult to make them unique. I picked up Algorithm Design Manual to read about random number generation. It has the following paragraph that I am fully not able to understand. Unfortunately, generating random numbers looks a lot easier than it really is. Indeed, it is fundamentally impossible to produce truly random numbers on any deterministic device. Von Neumann [Neu63] said it best: “Anyone who considers arithmetical methods of producing random digits is, of course, in a state of sin.” The best we can hope for are pseudo-random numbers, a stream of numbers that appear as if they were generated randomly. Why is it impossible to produce truly random numbers in any deterministic device? What does this sentence mean?

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  • How can Swift be so much faster than Objective-C?

    - by Yellow
    Apple launched its new programming language Swift today. In the presentation, they made some performance comparisons between Objective-C and Python. The following is a picture of one of their slides, of a comparison of those three languages performing some complex object sort: There was an even more incredible graph about a performance comparison working on some encryption algorithm. Obviously this is a marketing talk, and they didn't go into detail on how this was implemented in each. I leaves me wondering though: how can a new programming language be so much faster? In this example, surely you just have a bad Objective-C compiler or you're doing something in a less efficient way? How else would you explain a 40% performance increase? I understand that garbage collection/automated reference control might produce some additional overhead, but this much?

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  • How do I detect multiple sprite collisions when there are >10 sprites?

    - by yao jiang
    I making a small program to animate the astar algorithm. If you look at the image, there are lots of yellow cars moving around. Those can collide at any moment, could be just one or all of them could just stupidly crash into each other. How do I detect all of those collisions? How do I find out which specific car has crash into which other car? I understand that pygame has collision function, but it only detects one collision at a time and I'd have to specify which sprites. Right now I am just trying to iterate through each sprite to see if there is collision: for car1 in carlist: for car2 in carlist: collide(car1, car2); This can't be the proper way to do it, if the car list goes to a huge number, a double loop will be too slow.

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  • How to credit other authors in an open source project

    - by erik
    I have a pet project that I am planning to release as open source at some point in the not-too-distant future. A couple of the files use or are mostly code that was taken from a project released under the New BSD License. While I have changed it to fit my needs and added some small stuff, the algorithm and the functionality is basically exactly the same. I want to make sure that the author of the code gets credit and that the license is not broken, but I also want to make the reader aware that this is not the code as it was orignally released. How should I approach this? Should I isolate the code as much as possible and just retain the original license? Maybe put all the files that contain foreign code in their own folder and add a readme explaining what has been added/removed? There must have been tons of projects using other open source code. What is the standard approach to this?

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  • How does bing-bot( is that the right spider-name? ) and googlebot interpret 301 redirect?

    - by jbcurtin
    I've been looking for documentation on how the Microsoft and Google bots interpret 301 redirects. It seems that google-bot stores documents on a url based index system. But I haven't been able to figure out how bing works. Should I assume that they are still working towards coping everyone else and assume they use an algorithm close to google? Is it best to just forward a page to a new location via Javascript? I think this might be a blackhat trick, but how would I tell the bots that it's not? Is 301 redirect my best option and I just have to bit the bullet because said pages are no longer in existence? What other options do I have that I might not be aware of?

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  • The Excel Column Name assigment problem

    - by Peter Larsson
    Here is a generic algorithm to get the Excel column name according to it's position. By changing the @Base parameter, you can do this for any sequence according to same style as Excel. DECLARE @Value INT = 8839,         @Base TINYINT = 26   ;WITH cteSequence(Value, Delta, Quote, Base, Chr) AS (     SELECT  CAST(@Value AS INT) AS Value,             CAST(1 AS INT) AS Delta,             CAST(@Base AS INT) AS Quote,             CAST(@Base AS INT) AS Base,             CHAR(65 +(@Value - 1) % @Base) AS Chr       UNION ALL       SELECT  Value AS Value,             Quote AS Delta,             26 * Quote AS Quote,             Base AS Base,             CHAR(65 +((Value - Delta)/ Quote - 1) % Base) AS Chr     FROM    cteSequence     WHERE   CHAR(65 +((Value - Delta)/ Quote - 1) % Base) <> '@' ) SELECT  CAST(Msg AS VARCHAR(MAX)) FROM    (             SELECT        '' + Chr             FROM        cteSequence             ORDER BY    Delta DESC             FOR XML        PATH('')         ) AS x(Msg)

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  • Abstract Data Type and Data Structure

    - by mark075
    It's quite difficult for me to understand these terms. I searched on google and read a little on Wikipedia but I'm still not sure. I've determined so far that: Abstract Data Type is a definition of new type, describes its properties and operations. Data Structure is an implementation of ADT. Many ADT can be implemented as the same Data Structure. If I think right, array as ADT means a collection of elements and as Data Structure, how it's stored in a memory. Stack is ADT with push, pop operations, but can we say about stack data structure if I mean I used stack implemented as an array in my algorithm? And why heap isn't ADT? It can be implemented as tree or an array.

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  • Moving around/avoiding obstacles

    - by János Harsányi
    I would like to write a "game", where you can place an obstacle (red), and then the black dot tries to avoid it, and get to the green target. I'm using a very easy way to avoid it, if the black dot is close to the red, it changes its direction, and moves for a while, then it moves forward to the green point. How could I create a "smooth" path for the computer controlled "player"? Edit: Not the smoothness is the main point, but to avoid the red blocking "wall" and not to crash into it and then avoid it. How could I implement some path finding algorithm if I just have basically 3 points? (And what would it make the things much more complicated, if you could place multiple obstacles?)

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  • How to round currency values [migrated]

    - by Kenny
    I already have several ways to solve this, but I am interested in whether there is a better solution to this problem. Please only respond with a pure numeric algorithm. String manipulation is not acceptable. I am looking for an elegant and efficient solution. Given a currency value (ie $251.03), split the value into two half and round to two decimal places. The key is that the first half should round up and the second should round down. So the outcome in this scenario should be $125.52 and $125.51.

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  • Google keeps indexing /comment/reply URL

    - by jaypabs
    With the new update of Google algorithm called Penguin, I think my site was being penalized due to webspam. But of course I don't create post which seems to be spam to Google. It is just I think how Google index my site. I found out that Google index the URL of my site like: http://www.example.com/comment/reply/3866/26556 So there are so many comment/reply URL index by Google. I have already added: Disallow: /comment/reply/ Disallow: /?q=comment/reply/ but still Google still index this URL. Any idea how to prevent Google from indexing comments?

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  • Wireless not working on Dell XPS 17 after installing 12.04

    - by user60622
    I (linux newbie) have a Dell XPS 17 and tried to install Ubuntu 12.04. After installation all WLAN accesspoints near are detected. But I can not connect (but I am able to connect with other computers as well as with Dell XPS 17 under windows). Outputs: iwconfig lo no wireless extensions. wlan0 IEEE 802.11bg ESSID:"LerchenPoint" Mode:Managed Frequency:2.412 GHz Access Point: 58:6D:8F:A0:2D:58 Bit Rate=1 Mb/s Tx-Power=14 dBm Retry long limit:7 RTS thr:off Fragment thr:off Power Management:off Link Quality=70/70 Signal level=-37 dBm Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0 Tx excessive retries:0 Invalid misc:19 Missed beacon:0 eth0 no wireless extensions. sudo lshw -class network *-network description: Wireless interface product: Centrino Wireless-N 1000 vendor: Intel Corporation physical id: 0 bus info: pci@0000:04:00.0 logical name: wlan0 version: 00 serial: 00:26:c7:99:98:28 width: 64 bits clock: 33MHz capabilities: pm msi pciexpress bus_master cap_list ethernet physical wireless configuration: broadcast=yes driver=iwlwifi driverversion=3.2.0-24-generic firmware=39.31.5.1 build 35138 latency=0 link=no multicast=yes wireless=IEEE 802.11bg resources: irq:50 memory:f0400000-f0401fff *-network description: Ethernet interface product: RTL8111/8168B PCI Express Gigabit Ethernet controller vendor: Realtek Semiconductor Co., Ltd. physical id: 0 bus info: pci@0000:0a:00.0 logical name: eth0 version: 06 serial: f0:4d:a2:56:e3:94 size: 1Gbit/s capacity: 1Gbit/s width: 64 bits clock: 33MHz capabilities: pm msi pciexpress msix vpd bus_master cap_list ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt 1000bt-fd autonegotiation configuration: autonegotiation=on broadcast=yes driver=r8169 driverversion=2.3LK-NAPI duplex=full firmware=rtl_nic/rtl8168e-2.fw ip=192.168.0.123 latency=0 link=yes multicast=yes port=MII speed=1Gbit/s resources: irq:47 ioport:6000(size=256) memory:f0a04000-f0a04fff memory:f0a00000-f0a03fff dmesg | grep iwl [ 10.157531] iwlwifi 0000:04:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17 [ 10.157561] iwlwifi 0000:04:00.0: setting latency timer to 64 [ 10.157598] iwlwifi 0000:04:00.0: pci_resource_len = 0x00002000 [ 10.157599] iwlwifi 0000:04:00.0: pci_resource_base = ffffc90011090000 [ 10.157601] iwlwifi 0000:04:00.0: HW Revision ID = 0x0 [ 10.157731] iwlwifi 0000:04:00.0: irq 50 for MSI/MSI-X [ 10.157834] iwlwifi 0000:04:00.0: Detected Intel(R) Centrino(R) Wireless-N 1000 BGN, REV=0x6C [ 10.157976] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S [ 10.179772] iwlwifi 0000:04:00.0: device EEPROM VER=0x15d, CALIB=0x6 [ 10.179775] iwlwifi 0000:04:00.0: Device SKU: 0X50 [ 10.179777] iwlwifi 0000:04:00.0: Valid Tx ant: 0X1, Valid Rx ant: 0X3 [ 10.179796] iwlwifi 0000:04:00.0: Tunable channels: 13 802.11bg, 0 802.11a channels [ 10.574728] iwlwifi 0000:04:00.0: loaded firmware version 39.31.5.1 build 35138 [ 10.726409] ieee80211 phy0: Selected rate control algorithm 'iwl-agn-rs' [ 19.714132] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S [ 19.777862] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S [ 2251.603089] iwlwifi 0000:04:00.0: PCI INT A disabled [ 2266.578350] iwlwifi 0000:04:00.0: PCI INT A -> GSI 17 (level, low) -> IRQ 17 [ 2266.578399] iwlwifi 0000:04:00.0: setting latency timer to 64 [ 2266.578435] iwlwifi 0000:04:00.0: pci_resource_len = 0x00002000 [ 2266.578437] iwlwifi 0000:04:00.0: pci_resource_base = ffffc90011090000 [ 2266.578439] iwlwifi 0000:04:00.0: HW Revision ID = 0x0 [ 2266.578704] iwlwifi 0000:04:00.0: irq 50 for MSI/MSI-X [ 2266.578808] iwlwifi 0000:04:00.0: Detected Intel(R) Centrino(R) Wireless-N 1000 BGN, REV=0x6C [ 2266.578916] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S [ 2266.600709] iwlwifi 0000:04:00.0: device EEPROM VER=0x15d, CALIB=0x6 [ 2266.600712] iwlwifi 0000:04:00.0: Device SKU: 0X50 [ 2266.600713] iwlwifi 0000:04:00.0: Valid Tx ant: 0X1, Valid Rx ant: 0X3 [ 2266.600727] iwlwifi 0000:04:00.0: Tunable channels: 13 802.11bg, 0 802.11a channels [ 2266.605978] iwlwifi 0000:04:00.0: loaded firmware version 39.31.5.1 build 35138 [ 2266.606331] ieee80211 phy0: Selected rate control algorithm 'iwl-agn-rs' [ 2266.614179] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S [ 2266.681541] iwlwifi 0000:04:00.0: L1 Enabled; Disabling L0S Solutions I tried: rfkill list all 0: dell-wifi: Wireless LAN Soft blocked: no Hard blocked: no 2: phy0: Wireless LAN Soft blocked: no Hard blocked: no echo "options iwlwifi 11n_disable=1" | sudo tee /etc/modprobe.d/iwlwifi.conf options iwlwifi 11n_disable=1 sudo modprobe -rfv iwlwifi WARNING: All config files need .conf: /etc/modprobe.d/blacklist, it will be ignored in a future release. rmmod /lib/modules/3.2.0-24-generic/kernel/drivers/net/wireless/iwlwifi/iwlwifi.ko rmmod /lib/modules/3.2.0-24-generic/kernel/net/mac80211/mac80211.ko rmmod /lib/modules/3.2.0-24-generic/kernel/net/wireless/cfg80211.ko sudo modprobe iwlwifi WARNING: All config files need .conf: /etc/modprobe.d/blacklist, it will be ignored in a future release. replacing iwlwifi-1000-5.ucode (current driver) against iwlwifi-1000-3.ucode sudo jockey-gtk: (jockey-gtk:2493): Gtk-CRITICAL **: gtk_icon_set_render_icon_pixbuf: assertion icon_set != NULL' failed (jockey-gtk:2493): Gtk-CRITICAL **: gtk_icon_set_render_icon_pixbuf: assertion icon_set != NULL' failed nothing is listet in "Additional drivers" (german: "Zusätzliche Treiber"). gksudo gedit /etc/modprobe.d/blacklist.conf add "blacklist acer_wmi" Any help would be appreciated very much. Thanks!!

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  • Google I/O 2010 - Next gen queries

    Google I/O 2010 - Next gen queries Google I/O 2010 - Next gen queries App Engine 301 Alfred Fuller This session will discuss the design and implications of improvements to the Datastore query engine including support for AND, OR and NOT query operators, the solution to exploding indexes and paging backwards with Cursors. Specific technologies discussed will be an improved zigzag merge join algorithm, a new extensible multiquery framework (with geo-query support) and a smaller more versatile Cursor design. For all I/O 2010 sessions, please go to code.google.com From: GoogleDevelopers Views: 16 1 ratings Time: 50:17 More in Science & Technology

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  • How to change the sprite colors

    - by Mr_Qqn
    In my rhythm game, I have a note object which can be of different colors depending on the note chart. I could use a sprite sheet with all the different color variations I use, but I would prefer to parametrize this. (For information, a note sprite is compound with one main color, for example a red note has only red, light red and dark red.) So, how to change the colors of a sprite basing on a new color ? I'm working with opengl, but any algorithm or math explanation will do. :) Thanks

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  • deciphering columnar transposition cipher

    - by Arfan M
    I am looking for an idea on how to decipher a columnar transposition cipher without knowing the key or the length of the key. When I take the cipher text as input to my algorithm I will guess the length of the key to be the factors of the length of the cipher text. I will take the first factor suppose the length was 20 letters so I will take 2*10 (2 rows and 10 columns). Now I want to arrange the cipher text in the columns and read it row wise to see if there is any word forming and match it with a dictionary if it is something sensible. If it matches the dictionary then it means it is in correct order or else I want to know how to make other combinations of the columns and read the string again row wise. Please suggest another approach that is more efficient.

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  • Improving mdadm RAID-6 write speed

    - by BarsMonster
    Hi! I have a mdadm RAID-6 in my home server of 5x1Tb WD Green HDDs. Read speed is more than enough - 268 Mb/s in dd. But write speed is just 37.1 Mb/s. (Both tested via dd on 48Gb file, RAM size is 1Gb, block size used in testing is 8kb) Could you please suggest why write speed is so low and is there any ways to improve it? CPU usage during writing is just 25% (i.e. half of 1 core of Opteron 165) No business critical data there & server is UPS-backed. mdstat is: Personalities : [raid6] [raid5] [raid4] md0 : active raid6 sda1[0] sdd1[4] sde1[3] sdf1[2] sdb1[1] 2929683456 blocks super 1.2 level 6, 1024k chunk, algorithm 2 [5/5] [UUUUU] bitmap: 0/8 pages [0KB], 65536KB chunk unused devices: <none> Any suggestions?

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  • Auto-tiling with Yoshi's Island style tiles

    - by Boreal
    I'm creating a 2D platformer and I'd like to implement an auto-tiling system. Normally, this wouldn't be particularly difficult. However, I'd like to have tiles like in Yoshi's Island, where the graphics extend past the actual collidable tile's boundaries. Consider this image: Although the eggs and the Piranha Plant are clearly resting on the ground, the flower tiles continue behind them, out of the collidable tile. I know that it would be simple to do by hand, but extremely time consuming. Using an auto-tiling algorithm would save me a lot of time and boredom, but I'm not sure where to start.

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  • Electronic circuit simulator four-way flood-filling issues

    - by AJ Weeks
    I've made an electronic circuit board simulator which has simply 3 types of tiles: wires, power sources, and inverters. Wires connect to anything they touch, other than the sides of inverters; inverters have one input side and one output side; and finally power tiles connect in a similar manner as wires. In the case of an infinite loop, caused by the output of the inverter feeding into its input, I want inverters to oscillate (quickly turn on/off). I've attempted to implement a FloodFill algorithm to spread the power throughout the grid, but seem to have gotten something wrong, as only the tiles above the power source get powered (as seen below) I've attempted to debug the program, but have had no luck thus far. My code concerning the updating of power can be seen here.

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  • modifying openssl library code

    - by Nouar Ismail
    I am ordered to check the availability to customize an encryption algorithm the IPsec protocol use in Ubuntu, if anyone have any suggestion about this point?. I've read that the encryption operation occur in libcrypto in openssl. when I tried to compile and install OpenSSL from source ..I had everything ok with the installation, but when to check the version installed on the system, with "dpkg -s openssl", it didn't seem that it's the version i had already installed, maybe it had been installed successfully, but the question is: would it be the version the system use for encryption operations? would it overwrite the old version? and would my changes in code have effects ? any help please? thank you in advance.

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  • Is there an open source sports manager project?

    - by massive
    For a long time I've tried to search for an open source manager game, but without any luck. I'm looking for a suitable project for a reference to my own pet project. Features like well designed data model, tournament and fixture generation and understandable match simulation algorithm would be a great bonuses. I'm especially interested in game projects like Hattrick and SI Games' Football Manager, although it is irrelevant what the particular sport is. The project should be preferably web-based as Hattrick is. I've crawled through GitHub and SourceForge, but I found only a few sports simulation projects. Projects, which I have found, were either dead or not fulfilling my wishes. Do you know any open source manager game / fantasy sports game project, which would be available as open source, OR at least any material, which would be useful when building a such project?

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  • Lighting a Voxel World Realistically

    - by sharethis
    I am new to game development and never implemented a complicated (and realistic) lighting. My game uses a 3d voxel terrain world (like Minecraft). To hold the data I use octrees. My goal is to render a more realistic world scene like in most voxel games. For that I want to use a bezier algorithm to round out the blocky world. Assume that I already have a large generated polygon of my terrain (or some of them). I heard of some techniques like volumetric light, global illumination, ... What approaches of a very realistic lighting are there for my "organic shaped" voxel game?

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  • Checker AI in visual basic not working [on hold]

    - by Eugene Galkine
    I am trying to a make checkers in visual basic with ai. I am using the minimax algorithm (or at least what I understand of it) and it works, except the ai is retarded and plays like it is trying to loose and I tried to switch around the min and the max but the results are IDENTICAL. I am pissed of and have been trying to fix it for over a week now, I would really appreciate it if someone could help me out here. I have 3 years experience of programming (in Java, only about of month of VB experience) and I always am able to solve all my errors on my own so I don't know why I can't get this to work. The program is not at all optimized or anything at this point and is over 1.2K lines long, so here is the entire vb project instead: https://www.dropbox.com/sh/evii0jendn93ir2/9fntwH2dNW I would really appreciate any help I could get.

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  • How do I generate terrain like that of Scorched Earth?

    - by alex
    Hi, I'm a web developer and I am keen to start writing my own games. For familiarity, I've chosen JavaScript and canvas element for now. I want to generate some terrain like that in Scorched Earth. My first attempt made me realise I couldn't just randomise the y value; there had to be some sanity in the peaks and troughs. I have Googled around a bit, but either I can't find something simple enough for me or I am using the wrong keywords. Can you please show me what sort of algorithm I would use to generate something in the example, keeping in mind that I am completely new to games programming (since making Breakout in 2003 with Visual Basic anyway)?

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  • How do I resolve this exercise on C++? [closed]

    - by user40630
    (Card Shuffling and Dealing) Create a program to shuffle and deal a deck of cards. The program should consist of class Card, class DeckOfCards and a driver program. Class Card should provide: a) Data members face and suit of type int. b) A constructor that receives two ints representing the face and suit and uses them to initialize the data members. c) Two static arrays of strings representing the faces and suits. d) A toString function that returns the Card as a string in the form “face of suit.” You can use the + operator to concatenate strings. Class DeckOfCards should contain: a) A vector of Cards named deck to store the Cards. b) An integer currentCard representing the next card to deal. c) A default constructor that initializes the Cards in the deck. The constructor should use vector function push_back to add each Card to the end of the vector after the Card is created and initialized. This should be done for each of the 52 Cards in the deck. d) A shuffle function that shuffles the Cards in the deck. The shuffle algorithm should iterate through the vector of Cards. For each Card, randomly select another Card in the deck and swap the two Cards. e) A dealCard function that returns the next Card object from the deck. f) A moreCards function that returns a bool value indicating whether there are more Cards to deal. The driver program should create a DeckOfCards object, shuffle the cards, then deal the 52 cards. This above is the exercise I'm trying to solve. I'd be very much appreciated if someone could solve it and explain it to me. The main idea of the program is quite simple. What I don't get is how to build the constructor for the class DeckOfCards and how to generate the 52 cards of the deck with different suits and faces. Untill now I've managed to do this: #include <iostream> #include <vector> using namespace std; /* * */ /* a) Data members face and suit of type int. b) A constructor that receives two ints representing the face and suit and uses them to initialize the data members. c) Two static arrays of strings representing the faces and suits. d) A toString function that returns the Card as a string in the form “face of suit.” You can use the + operator to concatenate strings. */ class Card { public: Card(int, int); string toString(); private: int suit, face; static string faceNames[13]; static string suitNames[4]; }; string Card::faceNames[13] = {"Ace","Two","Three","Four","Five","Six","Seven","Eight","Nine","Ten","Queen","Jack","King"}; string Card::suitNames[4] = {"Diamonds","Clubs","Hearts","Spades"}; string Card::toString() { return faceNames[face]+" of "+suitNames[suit]; } Card::Card(int f, int s) :face(f), suit(s) { } /* Class DeckOfCards should contain: a) A vector of Cards named deck to store the Cards. b) An integer currentCard representing the next card to deal. c) A default constructor that initializes the Cards in the deck. The constructor should use vector function push_back to add each Card to the end of the vector after the Card is created and initialized. This should be done for each of the 52 Cards in the deck. d) A shuffle function that shuffles the Cards in the deck. The shuffle algorithm should iterate through the vector of Cards. For each Card, randomly select another Card in the deck and swap the two Cards. e) A dealCard function that returns the next Card object from the deck. f) A moreCards function that returns a bool value indicating whether there are more Cards to deal. */ class DeckOfCards { public: DeckOfCards(); void shuffleCards(); Card dealCard(); bool moreCards(); private: vector<Card> deck(52); int currentCard; }; int main(int argc, char** argv) { return 0; } DeckOfCards::DeckOfCards() { //I'm stuck here I have no idea of what to take out of here. //I still don't fully get the idea of class inside class and that's turning out as a problem. I try to find a way to set the suits and faces members of the class Card but I can't figure out how. for(int i=0; i<deck.size(); i++) { deck[i]//....There is no function to set them. They must be set when initialized. But how?? } } For easier reading: http://pastebin.com/pJeXMH0f

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  • How to refactor an OO program into a functional one?

    - by Asik
    I'm having difficulty finding resources on how to write programs in a functional style. The most advanced topic I could find discussed online was using structural typing to cut down on class hierarchies; most just deal with how to use map/fold/reduce/etc to replace imperative loops. What I would really like to find is an in-depth discussion of an OOP implementation of a non-trivial program, its limitations, and how to refactor it in a functional style. Not just an algorithm or a data structure, but something with several different roles and aspects - a video game perhaps. By the way I did read Real-World Functional Programming by Tomas Petricek, but I'm left wanting more.

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  • Finding an A* heuristic for a directed graph

    - by Janis Peisenieks
    In a previous question, I asked about finding a route (or path if you will) in a city. That is all dandy. The solution I chose was with the A* algorithm, which really seems to suit my needs. What I find puzzling is heuristic. How do I find one in an environment without constant distance between 2 nodes? Meaning, not every 2 nodes have the same distance between them. What I have is nodes (junctures), streets with weight (which may also be one-way), a start/finish node (since the start and end is always in the same place) and a goal node. In an ordinary case, I would just use the same way I got to goal to go back, but since one of the streets could have been a one-way, that may not be possible. The main question How do I find a heuristic in a directed graph?

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