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minimum spanning tree Kruskal

Pankaj Roy answered on October 18, 2022 Popularity 6/10 Helpfulness 1/10

answer minimum spanning tree Kruskal

related minimum spanning tree using kruskal algorithm

minimum spanning tree Kruskal

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// C++ program for the above approach 
  
#include <bits/stdc++.h> 
using namespace std; 
  
// DSU data structure 
// path compression + rank by union 
class DSU { 
    int* parent; 
    int* rank; 
  
public: 
    DSU(int n) 
    { 
        parent = new int[n]; 
        rank = new int[n]; 
  
        for (int i = 0; i < n; i++) { 
            parent[i] = -1; 
            rank[i] = 1; 
        } 
    } 
  
    // Find function 
    int find(int i) 
    { 
        if (parent[i] == -1) 
            return i; 
  
        return parent[i] = find(parent[i]); 
    } 
  
    // Union function 
    void unite(int x, int y) 
    { 
        int s1 = find(x); 
        int s2 = find(y); 
  
        if (s1 != s2) { 
            if (rank[s1] < rank[s2]) { 
                parent[s1] = s2; 
            } 
            else if (rank[s1] > rank[s2]) { 
                parent[s2] = s1; 
            } 
            else { 
                parent[s2] = s1; 
                rank[s1] += 1; 
            } 
        } 
    } 
}; 
  
class Graph { 
    vector<vector<int> > edgelist; 
    int V; 
  
public: 
    Graph(int V) { this->V = V; } 
  
    // Function to add edge in a graph 
    void addEdge(int x, int y, int w) 
    { 
        edgelist.push_back({ w, x, y }); 
    } 
  
    void kruskals_mst() 
    { 
        // Sort all edges 
        sort(edgelist.begin(), edgelist.end()); 
  
        // Initialize the DSU 
        DSU s(V); 
        int ans = 0; 
        cout << "Following are the edges in the "
                "constructed MST"
             << endl; 
        for (auto edge : edgelist) { 
            int w = edge[0]; 
            int x = edge[1]; 
            int y = edge[2]; 
  
            // Take this edge in MST if it does 
            // not forms a cycle 
            if (s.find(x) != s.find(y)) { 
                s.unite(x, y); 
                ans += w; 
                cout << x << " -- " << y << " == " << w 
                     << endl; 
            } 
        } 
        cout << "Minimum Cost Spanning Tree: " << ans; 
    } 
}; 
  
// Driver code 
int main() 
{ 
    Graph g(4); 
    g.addEdge(0, 1, 10); 
    g.addEdge(1, 3, 15); 
    g.addEdge(2, 3, 4); 
    g.addEdge(2, 0, 6); 
    g.addEdge(0, 3, 5); 
  
    // Function call 
    g.kruskals_mst(); 
  
    return 0; 
}

Popularity 6/10 Helpfulness 1/10 Language cpp

Source: www.geeksforgeeks.org

Tags: c++ minimum-spanning-tree

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Contributed on Dec 04 2023

Pankaj Roy

0 Answers Avg Quality 2/10

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minimum spanning tree using kruskal algorithm

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//User function Template for Java

/**
 *  ith value in adj vector contains information between the node connected to it and weight between them.
 *  Example. for a value 2 3 1, Node 2 and Node 3 has weight 1. adj[2] = {3,1} and adj[3] = {2,1}.
 *  n -> number of nodes
 *  m -> total number of edges
 *  return the mst value
 */

class DSU
{
    //Function to find the minimum spanning tree value using Kruskal.
    static int[] parents;
    static int[] ranks;
    static long kruskalDSU(ArrayList<Edge> adj, int n, int m)
    {
       ArrayList<EdgeSort> list=new ArrayList<>();
       parents=new int[n+1];
       ranks=new int[n+1];
       
       for(Edge e : adj)
        list.add(new EdgeSort(e));
       Collections.sort(list);    
       
       for(int i=1;i<=n;i++){
           parents[i]=i;
           ranks[i]=0;
       }
       int res=0;
       int s=0;
       for(int i=0;i<list.size() && s<m;i++){
           EdgeSort es=list.get(i);
           int xRep=find(es.a);
           int yRep=find(es.b);
           
           if(xRep!=yRep){
               res+=es.w;
               union(xRep,yRep);
               s++;
           }
       }
       return res;
    }
    
    private static int find(int a){
        if(parents[a]==a)
            return a;
        parents[a]=find(parents[a]);
        return parents[a];
    }
    
    private static void union(int a,int b){
        int aRep=find(a);
        int bRep=find(b);
        if(aRep==bRep)
            return;
        if(ranks[aRep]<ranks[bRep])
            parents[aRep]=bRep;
        else if(ranks[aRep]>ranks[bRep])
            parents[bRep]=aRep;
        else{
            parents[bRep]=aRep;
            ranks[aRep]++;
        }    
    }
    
    public static class EdgeSort implements Comparable<EdgeSort>{
        int a;
        int b;
        int w;
        EdgeSort(Edge e){
            a=e.src;
            b=e.des;
            w=e.wt;
        }
        public int compareTo(EdgeSort e){
            return w-e.w;
        }
    }
}

Popularity 9/10 Helpfulness 1/10 Language whatever

Source: Grepper

Tags: algorithm algo

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Contributed on Oct 18 2022

Sumit Rawal

0 Answers Avg Quality 2/10

minimum spanning tree Kruskal

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