渣渣写算法之丢手帕问题

Posted 2020-12-13 wwkk

约瑟夫问题（丢手帕）

 

 

下面是尝试的一些Demo写法，先不要在意代码上的细节

 

① 利用数组，还是这个块，因为数据结构简单

 1   public static void ThreeOut(int num, int outnum)
 2         {          
 3             int[] data = new int[num];
 4             for (int i = 0; i < num; i++)
 5             {
 6                 data[i]=i + 1;
 7             }          
 8             int index = 0;
 9             int count = 0;
10             for (int i = 0; ; i++)
11             {
12                 if (index >= data.Length)
13                 {
14                     index = 0;
15                 }
16 
17                 if (data[index] == 0)
18                 {
19                     i--;
20                     index++;
21                     continue;
22                 }
23                 if ((i + 1) % outnum == 0)
24                 {
25                   //  Console.WriteLine(data[index]);  输出每一个
26                     if (count >= data.Length - 1)
27                     {
28                         Console.WriteLine($"最后一个{ data[index]}");  //输出最后一个
29                         break;
30                     }
31                     count++;
32                     data[index] = 0;
33                 }
34                 index++;
35             }
36         }

View Code

 

②利用List，没有数组快

 1    public static void Second(int num,int outnum)
 2         {
 3             List<int> data = new List<int>();
 4             for (int i = 0; i < num; i++)
 5             {
 6                 data.Add(i+1);
 7             }
 8             int index = 0;
 9             for (int i = 0;; i++)
10             {
11                 if (index>= data.Count)
12                 {
13                     index = 0;
14                 }
15                 if (data.Count==1)
16                 { 
17                     Console.WriteLine($"最后一个{data[0]}"); //输出最后一个
18                     break;
19                 }                
20 
21                 if ((i + 1) % outnum == 0)
22                 {
23                     // Console.WriteLine(data[index]); //输出每一个
24                     data.Remove(data[index]);
25                 }
26                 else {
27                     index++;
28                 }               
29             }
30         }

View Code

 

③ 环形链表，慢

 1 private static void FirstOut(List<HHH> data,int num, int outnum)
 2         {
 3           
 4             int index = 0;
 5             for (int i = 0; ; i++)
 6             {
 7                 if (data.Count <= 0)
 8                 {
 9                     break;
10                 }
11 
12                 if (index > 0)
13                 {
14                     if (index >= data.Count)
15                     {
16                         index = 0;
17                     }
18                     data[index].Index = i + 1;
19                 }
20 
21                 if (data[index].Index % outnum == 0)
22                 {
23                     //   Console.WriteLine(data[index].Name); //输出每一个
24                     if (index == 0)
25                     {
26                         data[data.Count - 1].Next = data[index].Next;
27                     }
28                     else
29                     {
30                         data[index - 1].Next = data[index].Next;
31                     }
32                     if (data.Count <= 1)
33                     {
34                         Console.WriteLine($"最后一个{data[index].Name}");
35                         data.Remove(data[index]);
36                         break;
37                     }
38                     else {
39                         data.Remove(data[index]);
40                     }                   
41                 }
42                 else
43                 {
44                     index++;
45                 }
46             }
47         }

View Code

 1   private static List<HHH> CreateList(int num)
 2         {
 3             var first = new HHH()
 4             {
 5                 Index = 1,
 6                 Name = $"小孩1",
 7             };
 8             List<HHH> data = new List<HHH>() { first };
 9             for (int i = 2; i <= num; i++)
10             {
11                 var item = new HHH()
12                 {
13                     Name = $"小孩{i}",
14                 };
15                 data.Add(item);
16                 data[i - 2].Next = item;
17             }
18             data.Last().Next = first;
19             return data;
20         }

View Code

简单测试

 1   static void Main(string[] args)
 2         {
 3             int num = 50000;
 4             int outnum = 72;
 5             Stopwatch st = new Stopwatch();
 6             st.Start();
 7             Two.Second(num, outnum);
 8 
 9             st.Stop();
10             Console.WriteLine($"List耗时:{st.ElapsedMilliseconds}");
11             st.Reset();
12             st.Start();
13             Three.ThreeOut(num, outnum);
14             st.Stop();
15             Console.WriteLine($"数组耗时:{st.ElapsedMilliseconds}");
16              st.Reset();
17             List<HHH> data = CreateList(num);
18             st.Start();
19             //for (int i = 0; i < 300; i++)
20             //{          
21             FirstOut(data,num, outnum);
22             //}
23             st.Stop();
24             Console.WriteLine($"环形耗时:{st.ElapsedMilliseconds}");
25 
26             Console.ReadKey();
27      }

View Code

 

 所以优先使用简单的结构解决问题