Divide and Conquer Merge_sort
This is a discussion on Divide and Conquer Merge_sort within the C++ Programming forums, part of the General Programming Boards category; This code is supposed to sort an array using the divide-and-conquer method. But I think I mixed up the index. .
#include <iostream>
using namespace std;
void Merge(float *A , int p , int q , int r)
{
int n1 = q - p + 1;
int n2 = r - q;
float *L = new float [n1];
float *R = new float [n2];
int i , j;
for ( i = 0 ; i < n1 ; i++)
L[i] = A[p + i -1];
for ( j = 0 ; j < n2 ; j++)
R[j] = A[q + j];
i = 1;
j = 1;
for ( int k = p; k <= r ; k++)
{
if ( L[i] <= R[j])
{
A[k] = L[i];
++i;
}
else if (A[k] == R[j])
{
++j;
}
}
delete [] L;
delete [] R;
}
void Merge_Sort(float *A, int p, int r)
{
if ( p < r )
{
int q = (p+r)/2;
Merge_Sort(A,p,q);
Merge_Sort(A,q+1,r);
Merge(A,p,q,r);
}
}
int main()
{
int n = 8;
float A[] = {5,2,4,7,1,3,2,6};
for ( int i = 0 ; i < 8 ; i++)
std::cout << A[i] << std::endl;
Merge_Sort(A,1,7);
cout << endl;
for ( int i = 0 ; i < 8 ; i++)
std::cout << A[i] << std::endl;
return 0;
}#include <iostream>
using namespace std;
void Merge(float *A , int p , int q , int r)
{
int n1 = q - p + 1;
int n2 = r - q;
float *L = new float [n1];
float *R = new float [n2];
int i , j;
for ( i = 0 ; i < n1 ; i++)
L[i] = A[p + i -1];
for ( j = 0 ; j < n2 ; j++)
R[j] = A[q + j];
i = 1;
j = 1;
for ( int k = p; k <= r ; k++)
{
if ( L[i] <= R[j])
{
A[k] = L[i];
++i;
}
else if (A[k] == R[j])
{
++j;
}
}
delete [] L;
delete [] R;
}
void Merge_Sort(float *A, int p, int r)
{
if ( p < r )
{
int q = (p+r)/2;
Merge_Sort(A,p,q);
Merge_Sort(A,q+1,r);
Merge(A,p,q,r);
}
}
int main()
{
int n = 8;
float A[] = {5,2,4,7,1,3,2,6};
for ( int i = 0 ; i < 8 ; i++)
std::cout << A[i] << std::endl;
Merge_Sort(A,1,7);
cout << endl;
for ( int i = 0 ; i < 8 ; i++)
std::cout << A[i] << std::endl;
return 0;
}
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