【解惑】孜孜不倦，用足球赛程详解c#中的yield return用法

 1 public static (int, int)[][] BuildMatchesTable(int n)
 2 {
 3     var matches = new (int, int)[n - 1][];  // 创建一个二维数组，表示比赛表
 4     var teams = FairCycle(n).GetEnumerator();  // 获取一个循环迭代器，用于生成比赛对阵
 5     for (int i = 0; i 1; i++)
 6     {
 7         var round = new (int, int)[n / 2];  // 创建一个一维数组，表示当前轮次的比赛对阵
 8         for (int t = 0; t 2; t++)
 9         {
10             teams.MoveNext();  // 迭代到下一个比赛对阵
11             round[t] = teams.Current;  // 将当前比赛对阵添加到当前轮次的比赛表中
12         }
13         matches[i] = round;  // 将当前轮次的比赛表添加到总的比赛表中
14         // FairCycle函数会在这里负责循环到下一个比赛对阵
15     }
16     return matches;  // 返回生成的比赛表
17 }
18 
19 static IEnumerableint,int)> FairCycle(int n)
20 {
21     // 将数字1到n-1按顺时针方式排列
22     // 从12点钟方向开始，1位于12点钟位置
23     int p = 1;
24     while (true)
25     {
26         // 返回n和12点钟位置的数字
27         yield return (p, n);
28         // 然后返回12点钟左右两侧的数字配对
29         // 例如，11和1点钟，10和2点钟，以此类推
30         for (int i = 1; i 2; i++)
31         {
32             int l = p + i;
33             l = l > (n - 1) ? l - (n - 1) : l;  // 对n进行循环，但不包括n本身
34             int r = p + (n - 1) - i;
35             r = r > (n - 1) ? r - (n - 1) : r;
36             yield return (l, r);
37         }
38         // 将时钟旋转n/2，使得p + n/2现在位于12点钟位置
39         p += n / 2;
40         p = p > (n - 1) ? p - (n - 1) : p;
41         // 这将开始下一轮的配对
42     }
43 }

 1 using NUnit.Framework;
 2 using System;
 3 using System.Linq;
 4 using System.Collections.Generic;
 5 
 6 namespace Solution {
 7   
 8   [TestFixture]
 9   public class SolutionTest
10   {
11     [Test]
12     public void Test2Teams()
13     {
14       var expected = new []{ new []{(1, 2)} };
15 
16       var actual = Tournament.BuildMatchesTable(2);
17       Assert.That(actual, Has.Length.EqualTo(1), "Should have 1 round");
18       Assert.That(actual[0], Has.Length.EqualTo(1), "The round should have 1 match");
19       if(actual[0][0].Item1>actual[0][0].Item2) (actual[0][0].Item1, actual[0][0].Item2) = (actual[0][0].Item2, actual[0][0].Item1);
20       Assert.AreEqual(expected, actual, "The match should be team 1 vs team 2");
21     }
22     
23     [Test]
24     public void Test4Teams() => TestTeams(4);
25     
26     [Test]
27     public void Test20Teams() => TestTeams(20);
28     
29     [Te服务器托管网st]
30     public void TestRandom()
31     {
32       Random rand = new Random();
33       
34       TestTeams(2*(3+rand.Next(3)));
35       TestTeams(2*(6+rand.Next(4)));
36     }
37 
38     public void TestTeams(int numberOfTeams)
39     {
40       Listint> teamsExpected = Enumerable.Range(1, numberOfTeams).ToList();
41       HashSetint, int)> matchesExpected = new HashSetint, int)>();
42       foreach(var round in TournamentSolution.BuildMatchesTable(numberOfTeams))
43       {
44         foreach(var game in round) matchesExpected.Add(game.Item1>game.Item2?(game.Item2,game.Item1):(game.Item1, game.Item2));
45       }
46 
47       var actual = Tournament.BuildMatchesTable(numberOfTeams);
48       Assert.That(actual, Has.Length.EqualTo(numberOfTeams-1), $"Should have {numberOfTeams-1} rounds");
49       foreach(var round in actual)
50       {
51         Listint> teamsByRound = new Listint>();
52         Assert.That(round, Has.Length.EqualTo(numberOfTeams/2), $"Each round should have {numberOfTeams/2} matches");
53         foreach(var game in round)
54         {
55           Assert.That(game, Is.InstanceOf(typeof((int, int))), "Each match is a tupple of 2 teams");
56           teamsByRound.Add(game.Item1);
57           teamsByRound.Add(game.Item2);
58           Assert.True(matchesExpected.Remove(game.Item1>game.Item2?(game.Item2,game.Item1):(game.Item1, game.Item2)), $"{game} is a duplicate or doesn't exist");
59         }
60         teamsByRound.Sort();
61         Assert.AreEqual(teamsExpected, teamsByRound, "Each round should have matches with every team");
62       }
63       Assert.IsEmpty(matchesExpected, "At least one match isn't scheduled");
64     }
65   }
66 }
67 
68 public class TournamentSolution
69 {
70     public static (int, int)[][] BuildMatchesTable(int numberOfTeams)
71     {
72       Listint> teams = Enumerable.Range(1, numberOfTeams).ToList();
73       int roundsNbr = numberOfTeams-1, gamesNbr = numberOfTeams /2, rotatorID = roundsNbr-1, buffer = 0;
74       (int, int)[][] result = new (int, int)[roundsNbr][];
75 
76       for (int i=0; i)
77       {
78         result[i] = new (int, int)[gamesNbr];
79         
80         for (int j = 0; j 0 + j], teams[roundsNbr - j]);
81 
82         buffer = teams[rotatorID];
83         teams.RemoveAt(rotatorID);
84         teams.Insert(0, buffer);
85       }
86       
87       return result;
88     }
89 }