CODEWITHSUNDEEP
c#.netalgorithm
ripper234
ripper234

Reputation: 230018

Shortest code to calculate list min/max in .NET

I'd like something like

int minIndex = list.FindMin(delegate (MyClass a, MyClass b) {returns a.CompareTo(b);});

Is there a builtin way to do this in .NET?

Upvotes: 14

Views: 41375

Answers (4)

Ryan Lundy
Ryan Lundy

Reputation: 210130

Well, if you can't use .NET 3.5, you could always sort the list and then return list[0]. It might not be the fastest way, but it's probably the shortest code, especially if your class already implements IComparable.

List<SomeClass> list = new List<SomeClass>();
// populate the list
// assume that SomeClass implements IComparable
list.Sort();
return list[0];               // min, or
return list[list.Count - 1];  // max

This also assumes, of course, that it doesn't matter which item you return if you have multiple items that are the minimum or maximum.

If your class doesn't implement IComparable, you can pass in an anonymous delegate, something like this:

list.Sort(delegate(SomeClass x, SomeClass y) { return string.Compare(x.Name, y.Name); });

Upvotes: 14

Marc Gravell
Marc Gravell

Reputation: 1062745

You note that "I'm still in 2" - you might, then, want to look at LINQBridge. This is actually aimed at C# 3.0 and .NET 2.0, but you should be able to use it with C# 2.0 and .NET 2.0 - just you'll have to use the long-hand:

MyClass min = Enumerable.Min(list),
        max = Enumerable.Max(list);

Of course, it will be easier if you can switch to C# 3.0 (still targetting .NET 2.0).

And if LINQBridge isn't an option, you can implement it yourself:

static void Main()
{
    int[] data = { 3, 5, 1, 5, 5 };
    int min = Min(data);
}
static T Min<T>(IEnumerable<T> values)
{
    return Min<T>(values, Comparer<T>.Default);
}
static T Min<T>(IEnumerable<T> values, IComparer<T> comparer)
{
    bool first = true;
    T result = default(T);
    foreach(T value in values) {
        if(first)
        {
            result = value;
            first = false;
        }
        else
        {
            if(comparer.Compare(result, value) > 0) 
            {
                result = value;
            }
        }
    }
    return result;
}

Upvotes: 3

Nicholas Mancuso
Nicholas Mancuso

Reputation: 11877

Try looking at these:

Min

Max

As long as your class implements IComparable, all you have to do is:

List<MyClass> list = new List();
//add whatever you need to add

MyClass min = list.Min();
MyClass max = list.Max();

Upvotes: 24

Rune Grimstad
Rune Grimstad

Reputation: 36300

Using Linq you have the Min() and Max() functions.

So you can do list.AsQueryable().Min();

Upvotes: 2

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