测试某个点是否在某个范围内的例程。

Question

有人能帮我吗？

对于C#

我需要实现一个例程来测试某个点是否在一个范围内(数组)，C#

图中的范围是1-3,6-9，11-15。

我想使用二进制搜索，我使用了它，但有一个缺陷，因为它只能测试2个范围在这种情况下.如果我有2个范围，那么二进制搜索工作得很好，因为它给出了两个范围的IComparer中的两个事件。(1-3,6-9)

在我添加3个范围后，二进制搜索只给我两个范围，6-9，11-15

我用的是List> range，IComparer>

差不多吧

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

你需要更精确地描述这个问题.

1. 范围可能不重叠(或实现逻辑来合并它们)
2. 范围都是封闭区间，即1..3表示1 <= x <= 3

而且你不考虑(例如)[1.4]，意思是1 <= x<4

• 整数，等等，

将这些假设和一些需要您搜索Tuple<a,a>的a值(参见Comp()方法中的异常)作为假设，下面是如何实现您所追求的目标的示例.

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