算法：归并排序

2. 图示过程
   (1) 归并排序的流程



3. (2) 合并两个有序数组的流程



4. 
   



5. C++代码实现：

#include <bits/stdc++.h>
using namespace std;
void merge(int *a, int left, int mid, int right, int *temp)
{
  int i = left;
  int j = mid + 1;
  int t = 0;
  while (i <= mid && j <= right)
  {
    if (a[i] <= a[j])
      temp[t++] = a[i++];
    else
      temp[t++] = a[j++];
 
  }
  while (i <= mid)
    temp[t++] = a[i++];
  while (j <= right)
    temp[t++] = a[j++];
  t = 0;
  while (left <= right)
    a[left++] = temp[t++];
 
}
 
void mergesort(int *a, int left, int right, int *temp)
{
  if (left < right)
  {
    int mid = left + (right - left) / 2;
    mergesort(a, left, mid, temp);
    mergesort(a, mid + 1, right, temp);
    merge(a, left, mid, right, temp);
  }
}
 
int main()
{
  int n;
  cin>>n;
  int a[n];
  for(int i=0;i<n;i++)
    cin>>a[i];
  int len = sizeof(a) / sizeof(int);
  int *temp = (int *)malloc(sizeof(int)*len);
  mergesort(a, 0, len - 1, temp);
  for (int i = 0; i < len; i++)
    cout << a[i] << '\t' << endl;
  return 0;
}

运行效果：