ordering vector elements based on heuristic values

Hi,
I am trying to order elements of a vector based on heuristic values. For example, if I have a class, A, and a function,

Code:

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int evaluate(A &input);

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that returns the heuristic value of A, I want to define a function that orders a vector of A based on their heuristic values -

Code:

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vector<A> *order(vector<A> *input);

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What is the most efficient way of doing that?

Thank you very much

Code:

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std::sort(v.begin(),v.end(),evaluate);

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Thank you very much. That works nicely.

I have a question though. It seems to me that the compare function that is passed into sort has to take two parameters by value. However, the data type that I am working with here is ~200 bytes in size, and I want to avoid passing them around by value if possible. If I define the compare function to take parameters by reference, compilation fails. Is there any workaround or alternatives?

Thank you.

The function object that std::sort takes wants to know when one element is smaller than another. My mistake. What you want is this:

Code:

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class heuristic_order
{
    bool operator() (const A & left, const A & right)    //this'll inline.
    {
            return evaluate(left) < evaluate(right);
    }
};

// . . . . . . . . .

std::sort(v.begin(),v.end(),heuristic_order());

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And if references "won't compile," then something is wrong with your code (no offense). References are lovely. See how you can work in the above.

*edit* reference problems might have to do with const-ness. Use non-constant references only when you know that you will have to modify the variable to achieve your goal (in a particular scope). Otherwise (like in comparison and "heuristic" algorithms), use constant references.

Thank you very much, const-ness was indeed the problem.