对列表>进行排序

How would I go about sorting in descending order, a List<Tuple<int, int>> using the first element of the tuple as the value that determines the order? It has to be in-place and I only know how to do it using LINQ which returns a new list.

我将如何使用元组的第一个元素作为确定顺序的值，按降序排序，使用List >进行排序？它必须是就地的，我只知道如何使用LINQ返回一个新列表。

4 个解决方案

#1

You just need to provide an IComparer<Tuple<int, int>> or a Comparison<Tuple<int, int>> to the List<T>.Sort method. The latter is probably easier to specify inline:

您只需要向List .Sort方法提供IComparer >或Comparison >。后者可能更容易指定内联：

list.Sort((x, y) => y.Item1.CompareTo(x.Item1));

If you want to order by the first value and then the second value, it becomes a bit trickier, but still feasible. For example:

如果你想按第一个值和第二个值排序，它会变得有点棘手，但仍然可行。例如：

list.Sort((x, y) => {
    int result = y.Item1.CompareTo(x.Item1);
    return result == 0 ? y.Item2.CompareTo(x.Item2) : result;
});

EDIT: I've now amended the above to sort in descending order. Note that the right way to do this is to reverse the order of the comparison (y to x instead of x to y). You must not just negate the return value of CompareTo - this will fail when CompareTo returns int.MinValue.

编辑：我现在修改了上面的内容，按降序排序。请注意，正确的方法是颠倒比较的顺序（y到x而不是x到y）。你不能只是否定CompareTo的返回值 - 当CompareTo返回int.MinValue时，这将失败。

#2

Why not this?

为什么不呢？

List<Tuple<int, int>> list = ...
list = list.OrderBy(i => i.Item1).ToList();

Yes, it creates a new list, but I'm just interested - why don't you like this?

是的，它创建了一个新列表，但我只是感兴趣 - 为什么你不喜欢这个？

List<Tuple<int, int>> list = new List<Tuple<int, int>>
{
    new Tuple<int,int>(1,1),
    new Tuple<int,int>(0,2),
    new Tuple<int,int>(3,0)
};

list.Sort(Comparer<Tuple<int, int>>.Default);

produces:

生产：

0,2
1,1
3,0

And it's in-place, isn't it?

它是就地的，不是吗？

#3

Have you looked at the List<T>.Sort method? You can use an overload that takes a Comparison<T> delegate or an IComparer<T>:

你看过List .Sort方法了吗？您可以使用带有Comparison 委托或IComparer 的重载：

list.Sort((x,y)=> x.Item1.CompareTo(y.Item1));

#4

var listSort = from element in list orderby element.Item1  element.Item2 select element;

#1