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#include <fstream>
#include <iostream>
#include <string>
using namespace std;
struct Leader;
struct Follower;
struct Follower
{
Leader *adjacentLeader;
Follower *nextFollower;
};
struct Leader
{
std::string element;
int inDegree;
Leader *nextLeader;
Follower *firstFollower;
};
Leader *head, *tail, *p, *q, *r, *temp;
Follower *f;
string x, y;
int elementCount;
void TopologicalSort(ifstream&);
Leader* BuildList(string,Leader*&,Leader*&,int);
void PrintIn();
int main()
{
ifstream inFile;
TopologicalSort(inFile);
return 0;
}
void TopologicalSort(ifstream &inFile)
{
inFile.open("prerequisites_windows.txt");
if (!inFile.is_open())
{
cout << "error finding file" << endl;
return;
}
head = new Leader;
tail = head;
elementCount = 0;
getline(inFile,x);
while (!inFile.eof())
{
getline(inFile,y);
p = BuildList (x, head, tail, elementCount);
q = BuildList (y, head, tail, elementCount);
f = new Follower;
f -> adjacentLeader = q;
f -> nextFollower = p -> firstFollower;
p -> firstFollower = f;
q -> inDegree++;
getline(inFile,x);
}
PrintIn();
p = head;
head = NULL;
r = tail;
int i = 0;
while (p != r)
{
q = p;
p = p -> nextLeader;
if (q -> inDegree == 0)
{
q -> nextLeader = head;
head = q;
i++;
if (i == 1)
tail = q;
}
}
q = head;
r = tail;
while (q != NULL)
{
cout << q->element;
elementCount --;
f = q -> firstFollower;
q = q -> nextLeader;
while (f != NULL)
{
p = f-> adjacentLeader;
p -> inDegree--;
if (p -> inDegree == 0)
{
p -> nextLeader = NULL;
r -> nextLeader = p;
r = p;
if (q == NULL)
q = r;
}
f = f -> nextFollower;
}
}
if (elementCount != 0)
cout << "ERROR - SET NOT PARTIALLY ORDERED" << endl;
}
Leader* BuildList (string w, Leader* &head, Leader* &tail,int i)
{
Leader *h = head;
tail -> element = w;
while (h -> element != w)
h = h -> nextLeader;
if (h == tail)
{
tail = new Leader;
i++;
h -> inDegree = 0;
h -> firstFollower = NULL;
h -> nextLeader = tail;
}
return h;
}
void PrintIn()
{
temp = head;
int j = 0;
temp++;
while(temp != tail)
{
j++;
cout << "Leader " << j << endl;
cout << "Element = " << temp->element << endl;
cout << "inDegree = " << temp->inDegree << endl;
if (temp->firstFollower == NULL)
{
cout << "Follower 1 = N/A" << endl;
}
else
{
cout << "Follower 1 = " << temp->firstFollower->adjacentLeader->element << endl;
if (temp->firstFollower->nextFollower == NULL)
cout << "Follower 2 = N/A" << endl;
else
cout << "Follower 2 = " << temp->nextLeader->element;
}
temp++;
}
}
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