经典排序算法

快排：

static int partition(int[] unsorted, int low, int high)
        {
            int pivot = unsorted[low];
            while (low < high)
            {
                while (low < high && unsorted[high] > pivot) high--;
                unsorted[low] = unsorted[high];
                while (low < high && unsorted[low] <= pivot) low++;
                unsorted[high] = unsorted[low];
            }
            unsorted[low] = pivot;
            return low;
        }

        static void quick_sort(int[] unsorted, int low, int high)
        {
            int loc = 0;
            if (low < high)
            {
                loc = partition(unsorted, low, high);
                quick_sort(unsorted, low, loc - 1);
                quick_sort(unsorted, loc + 1, high);
            }
        }

　　桶排序：

static int[] bucket_sort(int[] unsorted, int maxNumber = 99)
        {
            int[] sorted = new int[maxNumber + 1];
            for (int i = 0; i < unsorted.Length; i++)
            {
                sorted[unsorted[i]] = unsorted[i];
            }
            return sorted;
        }

　　冒泡：

  static void bubble_sort(int[] unsorted)
        {
            for (int i = 0; i < unsorted.Length; i++)
            {
                for (int j = i; j < unsorted.Length; j++)
                {
                    if (unsorted[i] > unsorted[j])
                    {
                        int temp = unsorted[i];
                        unsorted[i] = unsorted[j];
                        unsorted[j] = temp;
                    }
                }
            }
        }

　　选择排序：

static void selection_sort(int[] unsorted)
        {
            for (int i = 0; i < unsorted.Length; i++)
            {
                int min = unsorted[i], min_index = i;
                for (int j = i; j < unsorted.Length; j++)
                {
                    if (unsorted[j] < min)
                    {
                        min = unsorted[j];
                        min_index = j;
                    }
                }
                if (min_index != i)
                {
                    int temp = unsorted[i];
                    unsorted[i] = unsorted[min_index];
                    unsorted[min_index] = temp;
                }
            }
        }

　　插入排序：

static void insertion_sort(int[] unsorted)
        {
            for (int i = 1; i < unsorted.Length; i++)
            {
                if (unsorted[i - 1] > unsorted[i])
                {
                    int temp = unsorted[i];
                    int j = i;
                    while (j > 0 && unsorted[j - 1] > temp)
                    {
                        unsorted[j] = unsorted[j - 1];
                        j--;
                    }
                    unsorted[j] = temp;
                }
            }
        }

　　归并排序：

//将有二个有序数列a[first...mid]和a[mid...last]合并。
void mergearray(int a[], int first, int mid, int last, int temp[])
{
    int i = first, j = mid + 1;
    int m = mid,   n = last;
    int k = 0;

    while (i <= m && j <= n)
    {
        if (a[i] <= a[j])
            temp[k++] = a[i++];
        else
            temp[k++] = a[j++];
    }

    while (i <= m)
        temp[k++] = a[i++];

    while (j <= n)
        temp[k++] = a[j++];

    for (i = 0; i < k; i++)
        a[first + i] = temp[i];
}
void mergesort(int a[], int first, int last, int temp[])
{
    if (first < last)
    {
        int mid = (first + last) / 2;
        mergesort(a, first, mid, temp);    //左边有序
        mergesort(a, mid + 1, last, temp); //右边有序
        mergearray(a, first, mid, last, temp); //再将二个有序数列合并
    }
}