算法复习1(冒泡、快排、折半)

冒泡

 static void BubbleSort()
        {
            int[] array = new int[] { 7, 3, 5, 8, 2 };

            for (int i = 0; i < array.Length; i++)
            {
                for (int j = 0; j < array.Length - i - 1; j++)
                {
                    if (array[j] > array[j + 1])
                    {
                        int temp = array[j];
                        array[j] = array[j + 1];
                        array[j + 1] = temp;
                    }
                }
            }
            Array.ForEach(array, p => Console.Write(p));
        }

快排

        static int QuickSort(int[] array, int low, int high)
        {
            if (low >= high) return -1;

            int keyIndex = low;
            int key = array[low];


            while (low < high)
            {
                while (low <= high)
                {
                    if (key > array[high])
                    {
                        Swap(array, keyIndex, high);
                        keyIndex = high;
                        break;
                    }
                    high--;
                }

                while (low < high)
                {
                    if (key < array[low])
                    {
                        Swap(array, low, keyIndex);
                        keyIndex = low;
                        break;
                    }
                    low++;
                }
            }

            return keyIndex;
        }

        static void QuickSortRecursion(int[] array, int i, int j)
        {
            int index = QuickSort(array, i, j);

            if (index == -1) return;

            QuickSortRecursion(array, i, index - 1);
            QuickSortRecursion(array, index + 1, j);
        }

二分

static int DichoFind(int[] array, int num)
        {
            int i = 0;
            int j = array.Length - 1;

            while (i <= j)
            {
                int mid = (i + j) / 2;

                if (array[mid] > num)
                {
                    j = mid - 1;
                }
                else if (array[mid] < num)
                {
                    i = mid + 1;
                }
                else
                {
                    return mid;
                }
            }

            return -1;
        }