C++实现五种排序方式

插入排序

#include <iostream>
using std::cout;
using std::endl;

void printArr(int arr[], int n)
{
  for (int i = 0; i < n; i++)
  {
    cout << arr[i] << "\t";
  }
  cout << endl;
}

void insert_sort(int arr[], int n)
{
  printArr(arr, n);

  for (int i = 1; i < n; i++)
  {
    // 如果当前元素小于前面的已经排序好的递增序列的最后一个元素
    if (arr[i] < arr[i - 1])
    {
      cout << "arr[" << i << "] < "
           << "arr[" << i - 1 << "] " << endl;
      int tmp = arr[i];
      // 我们需要将这个元素不断移动到对应的位置
      int j = i;
      for (j = i; j >= 1; j--)
      {
        cout << "j: " << j << "  arr[j-1]: " << arr[j - 1] << "  "
             << "tmp: " << tmp << endl;
        if (arr[j - 1] > tmp)
        {
          arr[j] = arr[j - 1];
          cout << "移动"
               << "arr[" << j + 1 << "]" << endl;
        }
        else
        {
          break;
        }
      }
      if (j != i)
      {
        arr[j] = tmp;
        printArr(arr, n);
      }
    }
  }
}

int main()
{
  const int num = 5;
  int arr[num] = {1, 4, 3, 6, 2};
  insert_sort(arr, num);
  return 0;
}

冒泡排序

#include <iostream >
using std::cout;
using std::endl;

void printArr(int arr[], int n)
{
  for (int i = 0; i < n; i++)
  {
    cout << arr[i] << "\t";
  }
  cout << endl;
}

void bubble_sort(int arr[], int n)
{
  bool flag = false;

  for (int i = 0; i < n; i++)
  {
    flag = false;
    // 外层循环i次之后，相当于排序好了i个位置
    for (int j = 0; j < n - i - 1; j++)
    {
      // 不断的将较大的值传递到后面去
      // 所以最后的数据是最大的
      if (arr[j + 1] < arr[j])
      {
        int tmp = arr[j];
        arr[j] = arr[j + 1];
        arr[j + 1] = tmp;
        flag = true;
      }
    }
    // 如果一趟过程中没有执行冒泡操作
    // 那么说明已经排序好了，可以结束
    if (!flag)
    {
      return;
    }
  }
}

int main()
{
  const int num = 5;
  int arr[num] = {1, 4, 3, 6, 2};
  cout << "排序之前: ";
  printArr(arr, num);
  bubble_sort(arr, num);
  cout << "排序之后: ";
  printArr(arr, num);
}

选择排序

#include <iostream>
using std::cout;
using std::endl;

void printArr(int arr[], int n)
{
  for (int i = 0; i < n; i++)
  {
    cout << arr[i] << "\t";
  }
  cout << endl;
}

// 每一次选择一个最小的值放到前面
void select_sort(int arr[], int n)
{
  printArr(arr, n);
  for (int i = 0; i < n; i++)
  {
    int min = arr[i];
    int index = i;
    // 遍历之后的元素，获取到最小的元素
    for (int j = i+1; j < n; j++)
    {
      if (arr[j] < min)
      {
        min = arr[j];
        index = j;
      }
    }

    // 交换最小值和第i个元素
    if (index != i)
    {
      int tmp = arr[i];
      arr[i] = arr[index];
      arr[index] = tmp;
    }
  }
  printArr(arr, n);
}

int main()
{
  const int num = 5;
  int arr[num] = {1, 4, 3, 6, 2};
  select_sort(arr, num);
  return 0;
}

归并排序

#include <iostream>
using std::cout;
using std::endl;

// 输出指定索引的
void printArr(const int *arr, int left, int right)
{
  for (int i = left; i <= right; i++)
  {
    cout << arr[i] << "\t";
  }
  cout << endl;
}

// 输出数组信息
void printArr(const int *arr, int n)
{
  printArr(arr, 0, n-1);
}

void merge(int *arr, const int left, const int mid, const int right)
{
  // cout << "enter merge function "<<endl;
  // 申请一个临时空间
  int *tmp = new int[right - left + 1];

  // 进行合并
  int i = left;
  int j = mid + 1;
  int k = 0;

  // 将[left, mid], [mid+1, right]两个有序数组进行合并
  while (i <= mid && j <= right)
  {
    if (arr[i] < arr[j])
    {
      tmp[k] = arr[i];
      k++;
      i++;
    }
    else
    {
      tmp[k] = arr[j];
      k++;
      j++;
    }
  }

  // cout << "merge first step done"<<endl;
  while (i <= mid)
  {
    tmp[k] = arr[i];
    k++;
    i++;
  }

  while (j <= right)
  {
    tmp[k] = arr[j];
    k++;
    j++;
  }
  // cout << "merge second stemp done"<<endl;
  // cout << "original: ";
  // printArr(arr, left, right);

  // cout << "tmp: ";
  // printArr(tmp, right-left+1);

  // 将数据赋值给arr对应的位置
  k = 0;
  for (int i = left; i <= right; i++)
  {
    arr[i] = tmp[k];
    k++;
  }
  // cout << "after: ";
  // printArr(arr, left, right);

  // 释放空间
  delete[] tmp;
}

void sort(int *arr, const int left, const int right)
{
  // cout << "sort: "<<left << " to " << right<<endl;
  if (left >= right)
  {
    return;
  }
  int mid = (right - left) / 2 + left;
  sort(arr, left, mid);
  sort(arr, mid + 1, right);
  merge(arr, left, mid, right);
}

void merge_sort(int *arr, const int n)
{
  sort(arr, 0, n - 1);
}

int main()
{
  const int num = 6;
  int arr[num] = {3, 4, 1, 6, 2, 5};
  cout << "排序之前: ";
  printArr(arr, num);
  merge_sort(arr, num);
  cout << "排序之后: ";
  printArr(arr, num);
  return 0;
}

快速排序

#include <iostream>
using std::cout;
using std::endl;

void printArr(const int *arr, int n)
{
  for (int i = 0; i < n; i++)
  {
    cout << arr[i] << "\t";
  }
  cout << endl;
}

void sort(int *arr, int left, int right)
{
  // 停止条件
  if (left >= right)
  {
    return;
  }

  // 选择轴心然后移动元素
  int pivot = arr[left];
  // cout << "pivot: " << pivot << endl;
  int i = left, j = right;

  while (left < right)
  {
    // cout << "left<right: " << left << " < " << right << endl;
    while (left < right && arr[right] > pivot)
    {
      right--;
    }
    // cout << "right  " << right << "----" << endl;
    if (left < right)
    {
      // cout << "swap: " << left << right << endl;
      arr[left] = arr[right];
      left++;
    }
    while (left < right && arr[left] < pivot)
    {
      left++;
    }
    // cout << "left: " << left << endl;
    if (left < right)
    {
      // cout << "swap: " << left << right << endl;
      arr[right] = arr[left];
      right--;
    }
  }

  arr[left] = pivot;

  sort(arr, i, left);
  sort(arr, left + 1, j);
}

void quick_sort(int *arr, int n)
{
  printArr(arr, n);
  sort(arr, 0, n - 1);
  printArr(arr, n);
}

int main()
{
  const int num = 6;
  int arr[num] = {3, 4, 1, 6, 2, 5};
  quick_sort(arr, num);
  return 0;
}

标签：arr,num,cout,int,printArr,C++,++,五种,排序
来源： https://blog.csdn.net/weixin_44676081/article/details/115276233