Return min/max number in nested list

Question

I'm trying to find the min/max number within a nested list using Linq.

An example class would be:

public class ListA
{
    public HashSet<HashSet<int>> nestedList;

    public ListA()
    {
        nestedList = new HashSet<HashSet<int>>()
        {
            new HashSet<int> { 1, 3, 5, 7 },
            new HashSet<int> { 2, 12, 7, 19 },
            new HashSet<int> { 6, 9 , 3, 14 }
        };
    }

    public int MaxNumber
    {
        // return the highest number in list
    }
}

In the example above, the minimum number would be 1 and the max number 19.

I'm struggling to get anything to get valid syntax. Anyone help?

Duplicate of [Linq expression to find the max value of a List>?](https://stackoverflow.com/questions/6381215/linq-expression-to-find-the-max-value-of-a-listlistint). — CodeCaster, Dec 04 '17 at 12:19

score 3 · Answer 1 · answered Dec 04 '17 at 12:20

SelectMany and Max will likely produce the result you desire.

Also consider using DefaultIfEmpty (with whatever default makes sense for your context) - this will ensure that Max doesn't throw an exception if nestedList is empty.

public int MaxNumber
{
    get { return nestedList.SelectMany(z => z).DefaultIfEmpty(0).Max(); }
}

score 2 · Accepted Answer · answered Dec 04 '17 at 12:17

2

nestedList.SelectMany(item => item).Max();

and

nestedList.SelectMany(item => item).Min();

answered Dec 04 '17 at 12:17

nvoigt

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How embarrassing - I was trying to use a second Select after SelectMany - thanks. – John Ohara Dec 04 '17 at 12:18

Return min/max number in nested list

2 Answers2