测试一个点是否在一个范围内的例程

Question

谁能帮帮我？

对于 C#

我需要实现一个例程来测试一个点是否在一个范围内（数组），C#

下图中的范围是[1-3],[6-9],[11-15]

我想使用二进制搜索之类的东西，我用过它但是有一个缺陷，因为在这种情况下它只能测试 2 个范围...... 如果我有 2 个范围，则二进制搜索效果很好，因为在 IComparer 中为 2 个范围提供了 2 个事件。 ([1-3],[6-9])

在我添加 3 个范围后，二进制搜索只给我 2 个范围，[6-9]、[11-15]

我正在使用 List> 范围和 IComparer>

类似的东西---

class RangeComparerPoint : IComparer<Tuple<int, int>>
    {
        public int Compare(Tuple<int, int> f1, Tuple<int, int> f2)
        {
            //for the sake of clarity
            int boundary_1 = f1.Item1;
            int boundary_2 = f1.Item2;
            int pos = f2.Item1;
            int currPos = f2.Item2;

            //EndSection 
            if (pos > currPos)
            {
                if (pos >= boundary_1 && currPos < boundary_1)
                {
                    //in the range
                    return 0;
                }
            }
            else
            {
                if ( boundary_1 > currPos )
                {
                    return -1;
                }

                if (pos <= boundary_1)
                {
                    //in the range
                    return 0;
                }
            }
            return -1;
        }
    }

Answer 1

你需要更准确地描述问题...

范围不能重叠（或实施合并它们的逻辑）
范围都是闭区间，即 [1..3] 表示 1 <= x <= 3
并且您不满足（比如）[1..4) 意思是 1 <= x < 4
仅限整数等等

将这些作为假设，需要您搜索 Tuple<a,a> 以获得值 a（请参阅 Comp() 方法中的异常），这是一个示例如何实现你所追求的...

using System;
using System.Collections;
using System.Collections.Generic;

namespace ConsoleApp2
{
  class Program
  {
    // x represents a point and y a range 
    // (params are swapped if necessary, i.e. if y is a point and x a range)
    // returns 0 if x falls within the range represented by y
    // returns -1 if x falls before y on the number line, +1 if it falls after y
    public static int Comp(Tuple<int, int> x, Tuple<int, int> y)
    {
      var fSwap = 1;
      if (x.Item1 != x.Item2) 
      {
        (x, y) = (y, x); // swap so that x is always the value being searched for
        fSwap = -1;
      }
      if (x.Item1 != x.Item2) // ***
        throw new Exception("The value being sought MUST be new Tuple(a,b) where a == b");
      return fSwap * (x.Item1 < y.Item1 ? -1 : x.Item1 > y.Item2 ? +1 : 0);
    }

    static void Main(string[] args)
    {
      // must be non-overlapping and increasing
      var ranges = new List<Tuple<int, int>>
      {
        new Tuple<int, int>(1, 3),
        new Tuple<int, int>(6, 9),
        new Tuple<int, int>(11,15)
      };

      for (int i = 0; i < 20; i++)
      {
        var foundIn = ranges.BinarySearch(new Tuple<int, int>(i, i), Comparer<Tuple<int, int>>.Create(Comp));
        if (foundIn < 0)
          Console.WriteLine($"{i} does not fall in any range");
        else
          Console.WriteLine($"{i} falls within [{ranges[foundIn].Item1},{ranges[foundIn].Item2}]");
      }
      Console.ReadKey();
    }
  }
}

给出结果...

0 does not fall in any range
1 falls within [1,3]
2 falls within [1,3]
3 falls within [1,3]
4 does not fall in any range
5 does not fall in any range
6 falls within [6,9]
7 falls within [6,9]
8 falls within [6,9]
9 falls within [6,9]
10 does not fall in any range
11 falls within [11,15]
12 falls within [11,15]
13 falls within [11,15]
14 falls within [11,15]
15 falls within [11,15]
16 does not fall in any range
17 does not fall in any range
18 does not fall in any range
19 does not fall in any range

测试一个点是否在一个范围内的例程

Routine that tests if a point is within a range

c#

arrays

range

icomparer