common sort algorithms

sort.cpp

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+
+//希尔
+void shellSort(int *a, int length)
+{
+    int i, j;
+    int increment = length;
+    int insertnum;
+    while (increment > 1)
+    {
+        increment = increment / 3 + 1;
+        for (i = increment; i < length; i++)
+        {
+            insertnum = a[i];
+            //插入排序。
+            j = i;
+            while (j - increment >= 0 && insertnum < a[j - increment])
+            {
+                a[j] = a[j - increment];
+                j = j - increment;
+            }
+            a[j] = insertnum;
+        }
+    }
+}
+
+//快排
+void quickSort(int *a, const int start, const int end)
+{
+    if (start >= end)
+        return;
+    int start_point = start;
+    int end_point = end;
+    int key = a[start];
+    while (start_point < end_point)
+    {
+        while (a[end_point] >= key&& end_point > start_point)
+        {
+            end_point--;
+        }
+        while (a[start_point] < key&&end_point>start_point)
+        {
+            start_point++;
+        }
+        if (end_point > start_point)
+        {
+            int temp = a[start_point];
+            a[start_point] = a[end_point];
+            a[end_point] = temp;
+        }
+    }
+    if (start_point == end_point)
+    {
+        int temp = a[start_point];
+        a[start_point] = a[start];
+        a[start] = temp;
+    }
+
+    if (start_point)
+        quickSort(a, 0, start_point - 1);
+    quickSort(a, start_point + 1, end);
+}
+
+//二叉查找
+int bSearch(int *a, int length, int num)
+{
+    int left = 0;
+    int right = length - 1;
+    int middle = -1;
+    while (left <= right)
+    {
+        middle = (right - left) / 2 + left;
+        if (num == a[middle])
+            return middle;
+        else
+        {
+            if (num > a[middle])
+            {
+                left = middle + 1;
+            }
+            else
+            {
+                right = middle - 1;
+            }
+        }
+    }
+    return -1;
+}
+
+//冒泡
+void bubbleSort(int *a, int length)
+{
+    for (int i = 0; i < length - 1; i++)
+        for (int j = 0; j < length - i - 1; j++)
+        {
+            //如果前面的数比后面大，进行交换
+            if (a[j] > a[j + 1]) {
+                int temp = a[j];
+                a[j] = a[j + 1];
+                a[j + 1] = temp;
+            }
+        }
+}
+
+//插入
+void insertSort(int *a, int length)
+{
+    if (length <= 1)
+        return;
+    int temp;
+    for (int i = 1; i < length; i++)
+    {
+        temp = a[i];
+        int j = i;
+        while (j>0 && a[j - 1] > temp)
+        {
+            a[j] = a[j - 1];
+            j--;
+        }
+        a[j] = temp;
+    }
+}
+
+//选择
+void selectSort(int *a, int length)
+{
+    for (int i = 0; i < length; i++)
+    {
+        int key = i;
+        for (int j = i + 1; j < length; j++) 
+        {
+            if (a[j] < a[key]) {
+                key = j;
+            }
+        }
+        if (key != i)
+        {
+            int temp = a[key];
+            a[key] = a[i];
+            a[i] = temp;
+        }
+    }
+}
+
+//归并
+void merge(int *a, int left, int mid, int right)
+{
+    int length = right - left + 1;
+    int *temp = new int[length];
+    int k = 0;
+    int i = left;
+    int j = mid + 1;
+    for (int n = 0; n < length; n++)
+    {
+        if (i <= mid && j <= right)
+        {
+            if (a[i] <= a[j])
+            {
+                temp[k++] = a[i];
+                i++;
+            }
+            else
+            {
+                temp[k++] = a[j];
+                j++;
+            }
+        }
+        else if (i <= mid)
+        {
+            temp[k++] = a[i++];
+        }
+        else
+        {
+            temp[k++] = a[j++];
+        }
+    }
+    for (int n = 0; n < length; n++)
+    {
+        a[left+n] = temp[n];
+    }
+}
+
+// 递归实现的归并排序
+void mergeSort(int *a, int left, int right)
+{
+    if (left == right)
+        return;
+    int mid = (left + right) / 2;
+    mergeSort(a, left, mid);
+    mergeSort(a, mid + 1, right);
+    merge(a, left, mid, right);
+}
+
+
+//堆排序--构建大根堆
+void heapAdjust(int *a, int parent, int length) 
+{
+    int temp = a[parent];
+    int child = 2 * parent + 1;
+
+    while (child < length) {
+        if (child + 1 < length && a[child] < a[child + 1]) 
+        {
+            child++;
+        }
+        if (temp >= a[child])
+            break;
+        else
+        {
+            a[parent] = a[child];
+            parent = child;
+            child = 2 * child + 1;
+        }
+    }
+    a[parent] = temp;
+}
+
+void heapSort(int * a, int length) 
+{
+    // 循环建立初始堆
+    for (int i = length / 2; i >= 0; i--) 
+    {
+        heapAdjust(a, i, length);
+    }
+
+    for (int i = length - 1; i > 0; i--) 
+    {
+        int temp = a[i];
+        a[i] = a[0];
+        a[0] = temp;
+        heapAdjust(a, 0, i);
+    }
+}
+
+int main()
+{
+    int a[9] = { 5, 2, 4, 6, 3, 10, 9, 8, 7 };
+    //bubbleSort(a, 9);
+    //selectSort(a, 9);
+    //insertSort(a, 9);
+    //heapSort(a, 9);
+    //mergeSort(a, 0, 8);
+    //shellSort(a, 9);
+    quickSort(a, 0, 8);
+    int b[6] = { 1, 3, 5, 7, 8, 10 };
+    int key = bSearch(b, 6, 10);
+    return 0;
+}