Kruskal_Algorithm.cpp

[PrajwalDev09]

#include

using namespace std;

class disjointset
{
public:
int djset[20];

disjointset(int v)
{
    for(int i=0;i<=v;i++)
    {
        djset[i] = i;
    }
}

int find_root(int v)
{
    while(v != djset[v])
    {
        v = djset[v];
    }
    return v;
}

void take_union(int v1, int v2)
{
    int r1 = find_root(v1);
    int r2 = find_root(v2);

    if(v1 == r1 && v2 == r2)
    {
        djset[v1] = v2;
    }
    else if(v1 != r1 && v2 == r2)
    {
        djset[v2] = v1;
    }
    else if(v1 == r1 && v2!= r2)
    {
        djset[v1] = v2;
    }
    else if(v1 != r1 && v2 != r2)
    {
        djset[r1] = r2;
    }
}

};
class edge
{
public:
int v1;
int v2;
int wt;
};

class graph
{
public:
int v;
int e;
edge ed[20];

graph(int vertices, int edges)
{
    v = vertices;
    e = edges;
}

void accept_graph();
void display_graph();
void kruskal_mst();
void sort_edges();

};

void graph::sort_edges()
{
edge temp;
for(int i=0;i<e;i++)
{
for(int j=0;j<e-i-1;j++)
{
if(ed[j].wt > ed[j+1].wt)
{
temp.v1 = ed[j].v1;
temp.v2 = ed[j].v2;
temp.wt = ed[j].wt;

          ed[j].v1 = ed[j+1].v1;
          ed[j].v2 = ed[j+1].v2;
          ed[j].wt = ed[j+1].wt;

          ed[j+1].v1 = temp.v1;
          ed[j+1].v2 = temp.v2;
          ed[j+1].wt = temp.wt;
        }
    }
}

}
void graph::kruskal_mst()
{
edge mst[20];
int mst_ctr = 0;
int mst_cost = 0;
disjointset dj(v);
sort_edges();
cout<<"\n Edges after sorting: ";
display_graph();
cout<<"\n";

for(int i=0;i<e;i++)
{
    int r1 = dj.find_root(ed[i].v1);
    int r2 = dj.find_root(ed[i].v2);
    if(r1 != r2)
    {
        mst[mst_ctr].v1 = ed[i].v1;
        mst[mst_ctr].v2 = ed[i].v2;
        mst[mst_ctr].wt = ed[i].wt;
        mst_ctr++;
        mst_cost = mst_cost + ed[i].wt;
        dj.take_union(ed[i].v1,ed[i].v2);
    }
}

cout<<"\n MST is : ";
for(int i=0;i<mst_ctr;i++)
{
    cout<<"\n   "<<mst[i].v1<<"     "<<mst[i].v2<<"     "<<mst[i].wt;
}
cout<<"\n Total cost of MST is: "<<mst_cost;

}
void graph::accept_graph()
{
for(int i=0;i<e;i++)
{
cout<<"\n Enter v1 :";
cin>>ed[i].v1;
cout<<"\n Enter v2 :";
cin>>ed[i].v2;
cout<<"\n Enter weight :";
cin>>ed[i].wt;
}
}

void graph::display_graph()
{
for(int i=0;i<e;i++)
{
cout<<"\n "<<ed[i].v1<<" "<<ed[i].v2<<" "<<ed[i].wt;
}
}

int main() //Main Function
{

int v, e;					//Variable Declaration
cout<<"Minimum Spanning Tree Using Krushkal Algorithm:-\n";
cout<<"\n Enter the number of vertics : ";
cin>>v;
cout<<"\n Enter the number of edges : ";
cin>>e;

graph g(v, e);					//Function Call
g.accept_graph();
g.display_graph();
g.kruskal_mst();

}