sort 排序

selection sort:

void selectionSort(int arr[], int n) {

      int i, j, minIndex, tmp;     

      for (i = 0; i < n - 1; i++) {

            minIndex = i;

            for (j = i + 1; j < n; j++)

                  if (arr[j] < arr[minIndex])

                        minIndex = j;

            if (minIndex != i) {

                  tmp = arr[i];

                  arr[i] = arr[minIndex];

                  arr[minIndex] = tmp;

            }

      }

}

quick sort:
ref:http://www.algolist.net/Algorithms/Sorting/Quicksort

void quickSort(int arr[], int left, int right) {

      int i = left, j = right;

      int tmp;

      int pivot = arr[(left + right) / 2];

      /* partition */

      while (i <= j) {

            while (arr[i] < pivot)

                  i++;

            while (arr[j] > pivot)

                  j--;

            if (i <= j) {

                  tmp = arr[i];

                  arr[i] = arr[j];

                  arr[j] = tmp;

                  i++;

                  j--;

            }

      };

      /* recursion */

      if (left < j)

            quickSort(arr, left, j);

      if (i < right)

            quickSort(arr, i, right);

}

bubble sort:

void bubbleSort(int numbers[], int array_size)
{
  int i, j, temp;

  for (i = 1; i < array_size; i++)
  {
    for (j = 0; j < array_size - i; j++)
    {
      if (numbers[j] > numbers[j+1])
      {
        temp = numbers[j];
        numbers[j] = numbers[j+1];
        numbers[j+1] = temp;
      }
    }
  }
}

merge sort:

public int[] msort(int[] a) {
    if (a.Length > 1) {
        int min = a.Length / 2;
        int max = min;

        int[] b = new int[min];
        int[] c = new int[max]; // dividing main array into two half arrays
        for (int i = 0; i < min; i++) {
            b[i] = a[i];
        }

        for (int i = min; i < min + max; i++) {
            c[i - min] = a[i];
        }

        b = msort(b);
        c = msort(c);

        int x = 0;
        int y = 0;
        int z = 0;

        while (b.Length != y && c.Length != z) {
            if (b[y] < c[z]) {
                a[x] = b[y];
                //r--
                x++;
                y++;
            } else {
                a[x] = c[z];
                x++;
                z++;
            }
        }

        while (b.Length != y) {
            a[x] = b[y];
            x++;
            y++;
        }

        while (c.Length != z) {
            a[x] = c[z];
            x++;
            z++;
        }
    }

    return a;
}