算法 - 选择排序（C#）

// --------------------------------------------------------------------------------------------------------------------
// <copyright file="Program.cs" company="Chimomo's Company">
//
// Respect the work.
//
// </copyright>
// <summary>
//
// The selection sort.
//
// 每一趟从待排序的数据元素中选出最小（或最大）的一个元素，顺序放在已排好序的数列的最后，直到全部待排序的数据元素排完为止。选择排序是不稳定的排序算法。
//
// </summary>
// --------------------------------------------------------------------------------------------------------------------

namespace CSharpLearning
{
using System;

/// <summary>
/// The program.
/// </summary>
public static class Program
{
/// <summary>
/// The main.
/// </summary>
public static void Main()
{
int[] a = { 1, 6, 4, 2, 8, 7, 9, 3, 10, 5 };
Console.WriteLine("Before Selection Sort:");
foreach (int i in a)
{
Console.Write(i + " ");
}

Console.WriteLine("\r\n\r\nIn Selection Sort:");
SelectionSort(a);
Console.WriteLine("\r\nAfter Selection Sort:");
foreach (int i in a)
{
Console.Write(i + " ");
}

Console.WriteLine(string.Empty);
}

/// <summary>
/// The selection sort.
/// </summary>
/// <param name="a">
/// The a.
/// </param>
private static void SelectionSort(int[] a)
{
for (int i = 0; i < a.Length - 1; i++)
{
int min = i; // 存储最小元素的index。

// 寻找最小元素的index。
for (int j = i + 1; j < a.Length; j++)
{
if (a[j] < a[min])
{
min = j;
}
}

int tmp = a[min];
a[min] = a[i];
a[i] = tmp;
Console.Write("Round {0}: ", i + 1);

// 打印数组。
foreach (int k in a)
{
Console.Write(k + " ");
}

Console.WriteLine(string.Empty);
}
}
}
}

// Output:
/*
Before Selection Sort:
1 6 4 2 8 7 9 3 10 5

In Selection Sort:
Round 1: 1 6 4 2 8 7 9 3 10 5
Round 2: 1 2 4 6 8 7 9 3 10 5
Round 3: 1 2 3 6 8 7 9 4 10 5
Round 4: 1 2 3 4 8 7 9 6 10 5
Round 5: 1 2 3 4 5 7 9 6 10 8
Round 6: 1 2 3 4 5 6 9 7 10 8
Round 7: 1 2 3 4 5 6 7 9 10 8
Round 8: 1 2 3 4 5 6 7 8 10 9
Round 9: 1 2 3 4 5 6 7 8 9 10

After Selection Sort:
1 2 3 4 5 6 7 8 9 10
*/