归并排序

归并排序

步骤：
1.分解
2.解决
3.合并

 #include<iostream>
using namespace std;
void Merge(int* a, int p, int q, int r)
{
 int n1 = q - p + 1;
 int n2 = r - q;
 int* L = new int[n1 + 1];
 int* R = new int[n2 + 1];
 for (int i = 0; i < n1; i++)
 {
  L[i] = a[p + i];
 }
 for (int j = 0; j < n2; j++)
 {
  R[j] = a[q + j + 1];
 }
 L[n1] = 1111;
 R[n2] = 1111;
 int i = 0, j = 0;
 for (int k = p; k <= r; k++)
 {
  if (L[i] <= R[j])
  {
   a[k] = L[i];
   i++;
  }
  else
  {
   a[k] = R[j];
   j++;
  }
 }
 delete[]L;
 delete[]R;
}
void MergeSort(int* a, int l, int r)
{
 if (l < r)
 {
  int m = (l + r) / 2;
  MergeSort(a, l, m);
  MergeSort(a, m + 1, r);
  Merge(a, l, m, r);
 }
}
int main()
{
 int a[10] = { 5,2,4,1,8,9,10,12,3,6 };
 for (int i = 0; i < 10; i++)
 {
  cout << a[i] << " ";
 }
 cout << endl;
 MergeSort(a, 0, 9);
 for (int i = 0; i < 10; i++)
 {
  cout << a[i] << " ";
 }
 cout << endl;
 return 0;
}

来源：CSDN

作者：欧阳渣儿

链接：https://blog.csdn.net/qq_45021488/article/details/103750924