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algorithmes with no executable example code

- by gcc

[link] http://stackoverflow.com/questions/2932016/parsing-of-mathematical-expressions (problem has been told before) ** program is to create the infix tree for the given math expression.** if the expression is given completely paranthesized then the out put is fine but when there are no paranthesis or some part paranthesized then the out put is wrong. cant get the idea how to solve. my problem is told above. I have some algorithm to solve my problem, but I have no simple code which will be guide for me. Can anyone give me simple code (not working code) so that I will try working to understand.(for a 3 hours ,I have been searching and reading some text to understand algorithm which is told above.Actually,there is no example code investigating how it is working. Can anyone send me example which is written in c not other language.

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Using items in a list as arguments

- by Travis Brown

Suppose I have a function with the following type signature: g :: a -> a -> a -> b I also have a list of as—let's call it xs—that I know will contain at least three items. I'd like to apply g to the first three items of xs. I know I could define a combinator like the following: ($$$) :: (a -> a -> a -> b) -> [a] -> b f $$$ (x:y:z:_) = f x y z Then I could just use g $$$ xs. This makes $$$ a bit like uncurry, but for a function with three arguments of the same type and a list instead of a tuple. Is there a way to do this idiomatically using standard combinators? Or rather, what's the most idiomatic way to do this in Haskell? I thought trying pointfree on a non-infix version of $$$ might give me some idea of where to start, but the output was an abomination with 10 flips, a handful of heads and tails and aps, and 28 parentheses. (NB: I know this isn't a terribly Haskelly thing to do in the first place, but I've come across a couple of situations where it seems like a reasonable solution, especially when using Parsec. I'll certainly accept "don't ever do this in real code" if that's the best answer, but I'd prefer to see some clever trick involving the ((->) r) monad or whatever.)

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parsing of mathematical expressions

- by gcc

(in c90) (linux) input: sqrt(2 - sin(3*A/B)^2.5) + 0.5*(C*~(D) + 3.11 +B) a b /*there are values for a,b,c,d */ c d input: cos(2 - asin(3*A/B)^2.5) +cos(0.5*(C*~(D)) + 3.11 +B) a b /*there are values for a,b,c,d */ c d input: sqrt(2 - sin(3*A/B)^2.5)/(0.5*(C*~(D)) + sin(3.11) +ln(B)) /*max lenght of formula is 250 characters*/ a b /*there are values for a,b,c,d */ c /*each variable with set of floating numbers*/ d As you can see infix formula in the input depends on user. My program will take a formula and n-tuples value. Then it calculate the results for each value of a,b,c and d. If you wonder I am saying ;outcome of program is graph. /sometimes,I think i will take input and store in string. then another idea is arise " I should store formula in the struct" but i don't know how I can construct the code on the base of structure./ really, I don't know way how to store the formula in program code so that I can do my job. can you show me? /* a,b,c,d is letters cos,sin,sqrt,ln is function*/

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Velocity CTP: can we 'search' for objects?

- by Stato Machino

It appears that 'tags' allow us to associate a 'search term' with the objects placed into the Velocity cache space. However, these can only be queried within a 'region'. Further, regions somehow limit the locality of objects in the cache to a single server (or maybe something kinda like that). So this appears to make it hard to perform any operation for which the unique Id of the cached item is not persisted or continuously available to the application that stores and retrieves objects to and from the cache. In any case, I can't see an easy way to 'cleanse' the cache of objects or to find objects across the entire cache that may share some prefix, postfix or infix values in the cache key so that i can clear out the cache of object repeatedly created in unit tests, for example. And I am unsure about the consequences of regions being associated with single server cache locations. So I would appreciate any help with the following questions: What is the difference between a 'distributed cache' (called a 'partitioned' cache??) when using regions, and a 'local cache'? 1.a. In particular, are the region-oriented values in a distributed cache visible through a cache factory that is configured to 'see' the entire cache space? Are the operations of creating and removing 'regions' efficient enough that it would be reasonable to create a region and a group of tags for each bundle of objects that need to be cached? 2.a. Or does this just push the problem of scoping the 'search for objects' up the chain because the ability of the DataCache object to query down through regions and tags as limited as querying for the cache keys of objects themselves. Thanks, Stato

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Code Golf: Countdown Number Game

- by Noldorin

Challenge Here is the task, inspired by the well-known British TV game show Countdown. The challenge should be pretty clear even without any knowledge of the game, but feel free to ask for clarifications. And if you fancy seeing a clip of this game in action, check out this YouTube clip. It features the wonderful late Richard Whitely in 1997. You are given 6 numbers, chosen at random from the set {1, 2, 3, 4, 5, 6, 8, 9, 10, 25, 50, 75, 100}, and a random target number between 100 and 999. The aim is to make use the six given numbers and the four common arithmetic operations (addition, subtraction, multiplication, division; all over the rational numbers) to generate the target - or as close as possible either side. Each number may only be used once at most, while each arithmetic operator may be used any number of times (including zero.) Note that it does not matter how many numbers are used. Write a function that takes the target number and set of 6 numbers (can be represented as list/collection/array/sequence) and returns the solution in any standard numerical notation (e.g. infix, prefix, postfix). The function must always return the closest-possible result to the target, and must run in at most 1 minute on a standard PC. Note that in the case where more than one solution exists, any single solution is sufficient. Examples: {50, 100, 4, 2, 2, 4}, target 203 e.g. 100 * 2 + 2 + (4 / 4) e.g. (100 + 50) * 4 * 2 / (4 + 2) {25, 4, 9, 2, 3, 10}, target 465 e.g. (25 + 10 - 4) * (9 * 2 - 3) {9, 8, 10, 5, 9, 7), target 241 e.g. ((10 + 9) * 9 * 7) + 8) / 5 Rules Other than mentioned in the problem statement, there are no further restrictions. You may write the function in any standard language (standard I/O is not necessary). The aim as always is to solve the task with the smallest number of characters of code. Saying that, I may not simply accept the answer with the shortest code. I'll also be looking at elegance of the code and time complexity of the algorithm! My Solution I'm attempting an F# solution when I find the free time - will post it here when I have something! Format Please post all answers in the following format for the purpose of easy comparison: Language Number of characters: ??? Fully obfuscated function: (code here) Clear (ideally commented) function: (code here) Any notes on the algorithm/clever shortcuts it takes.

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Creating my own Stack

- by Malaken

I am creating my own stack for my data structures class. For our assignment we are using the assignment to convert a real-time infix equation into a postfix equation. I thought my program: took input determines if it was digit or number(operand) prints it out determines if input is operator (+,-,/,*) adds to stack or prints out, depending on stack precedence Instead it prints out the operands as expect, but I get this error when I enter an operator .../dorun.sh line 33: 4136 Segmentation fault sh "$" [code] #include using namespace std; class DishWell{ public: char ReturnEnd(){ return Well.back(); } void Push(char x){ Well.push_back(x); } void Pop(){ Well.pop_back(); } bool IsEmpty(){ return Well.empty(); } private: vector<char> Well; }; #include <iostream> bool Precidence(char Input, char Stack){ int InputPrecidence,StackPrecidence; switch (Input){ case '*': InputPrecidence = 4; break; case '/': InputPrecidence = 4; break; case '+': InputPrecidence = 3; break; case '-': InputPrecidence = 3; break; case '(': InputPrecidence = 2; break; default: InputPrecidence = 0; } switch (Stack){ case '*': StackPrecidence = 4; break; case '/': StackPrecidence = 4; break; case '+': StackPrecidence = 3; break; case '-': StackPrecidence = 3; break; case '(': StackPrecidence = 2; break; default: StackPrecidence = 0; } if(InputPrecidence>StackPrecidence) return true; else return false; } int main(int argc, char** argv) { DishWell DishTray; char Input; bool InputFlag; InputFlag = true; while(InputFlag){ cin>>Input; if((((Input>='a'&&Input<='z')||(Input>='A'&&Input<='Z'))|| (Input>='0'&&Input<='9')))//If Digit or Number cout<<Input; if((Input=='*'||Input=='/'||Input=='+'||Input=='-')){//if operand if(Precidence(Input,DishTray.ReturnEnd())) DishTray.Push(Input); else if(!Precidence(Input,DishTray.ReturnEnd())) cout<<Input; } else if(!((((Input>='a'&&Input<='z')||(Input>='A'&&Input<='Z'))|| (Input>='0'&&Input<='9')))||((Input=='*'||Input=='/'||Input=='+'||Input=='-')))//if not digit/numer or operand InputFlag = false; } while(!DishTray.IsEmpty()){ cout<<DishTray.ReturnEnd(); DishTray.Pop(); } return 0; [code] My code is very length, I know, but I appreciate help. Especially any times for efficency or future coding. Thanks again P.S. Dr. Zemoudeh, this is your student Macaire

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