algorithm - What is the most efficient way to get all combinations? -

possible duplicate:
finding possible combinations of numbers reach given sum

problem

you have list of people input, each person has number of credits. given total has achieved using 1 or more persons credits. function should output combinations exist result in total.

for example see below:-

static void main(string[] args) {     int total = convert.toint32(args[0]);     var persons = new list<person>();     persons.add(new person { credits = 10, name="steve"});     persons.add(new person { credits = 5, name = "paul" });     persons.add(new person { credits = 4, name = "david" });     persons.add(new person { credits = 1, name = "kenneth" });      printallcombinations(persons, total); // function in question } public class person {     public string name { get; set; }     public int credits { get; set; } } 

in above example, given total of 10, printallcombinations function should output similar to:-

• combination 1) steve:10
• combination 2) paul: 5, david 4, kenneth 1
• combination 3) steve: 9, paul 1
• combination 4) steve: 5, paul 5
• ...etc

update: forgot mention, can use part of persons credits

the example used simplified, real scenario constrained having no more 100 people , total less 90.

what best solution?

you can read solutions ubiquitous problem in python, java or haskell here

finding possible combinations of numbers reach given sum

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based on edit specifying may take partial credits, should @ post:

generate list of combinations/sets of numbers limited supplies

my solution, written in c, equally applicable case.