Kruskal’s Minimum Spanning Tree Algorithm

Kruskal’s algorithm is a well-known algorithm for finding the minimum spanning tree of a graph. It is a greedy algorithm that makes use of the fact that the edges of a minimum spanning tree must form a subset of the edges of any other spanning tree.

In Kruskal’s algorithm, sort all edges of the given graph in increasing order. Then it keeps on adding new edges and nodes in the MST if the newly added edge does not form a cycle. It picks the minimum weighted edge at first and the maximum weighted edge at last. Thus we can say that it makes a locally optimal choice in each step in order to find the optimal solution. Hence this is a Greedy Algorithm.

How to find MST using Kruskal’s algorithm?

Below are the steps for finding MST using Kruskal’s algorithm:

  1. Sort all the edges in non-decreasing order of their weight. 
  2. Pick the smallest edge. Check if it forms a cycle with the spanning tree formed so far. If the cycle is not formed, include this edge. Else, discard it. 
  3. Repeat step#2 until there are (V-1) edges in the spanning tree.

Note: In Step 2 we can use Union Find to detect cycles.

Time Complexity: O(E * logE) or O(E * logV) 
Auxiliary Space: O(V + E), where V is the number of vertices and E is the number of edges in the graph.

Greedy Algorithm Notes for GATE Exam [2024]Fractional Knapsack ProblemOptimal File Merge PatternsPrim’s Algorithm for Minimum Spanning Tree (MST)

In the dynamic landscape of algorithmic design, Greedy Algorithms stand out as powerful tools for solving optimization problems. Aspirants preparing for the GATE Exam 2024 are poised to encounter a range of questions that test their understanding of Greedy Algorithms. These notes aim to provide a concise and insightful overview, unraveling the principles and applications of Greedy Algorithms that are likely to be scrutinized in the upcoming GATE examination.

Table of Content

  • Introduction to Greedy Algorithms:
  • Activity Selection Problem:
  • Job Sequencing Problem
  • Huffman Coding
  • Kruskal’s Minimum Spanning Tree Algorithm
  • Dijkstra’s shortest path algorithm
  • MCQ Questions for Greedy Algorithm

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