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Problem: Minimize Malware Spread

Medium
30 min
Explore how to minimize malware spread in a network by identifying and removing a key infected node. Learn to apply Union Find methods to analyze graph connectivity and limit infection, gaining skills to solve challenging problems involving graph-based malware propagation.

Statement

You’re given a network of nn nodes as an n×nn \times n adjacency matrix graph with the ithi^{th} node directly connected to the jthj^{th} node if graph[i][j] == 1.

A list of nodes, initial, is given, which contains nodes initially infected by malware. When two nodes are connected directly and at least one of them is infected by malware, both nodes will be infected by malware. This spread of malware will continue until every node in the connected component of nodes has been infected.

After the infection has stopped spreading, MM will represent the final number of nodes in the entire network that have been infected with malware.

Return a node from initial such that, when this node is removed from the graph, MM is minimized. If multiple nodes can be removed to minimize MM, return the node with the smallest index.

Note: If a node was removed from the initial list of infected nodes, it might still be infected later on due to the malware’s spread.

Constraints:

  • graph.length == graph[i].length
  • 22 \leq n 50\leq 50
  • graph[i][j] is 00 or 11.
  • graph[i][j] == graph[j][i]
  • graph[i][i] == 1
  • 11 \leq initial.length n\leq n
  • 00 \leq initial[i] n1\leq n - 1
  • All the integers in the initial are unique.
Problem
Ask
Submissions

Problem: Minimize Malware Spread

Medium
30 min
Explore how to minimize malware spread in a network by identifying and removing a key infected node. Learn to apply Union Find methods to analyze graph connectivity and limit infection, gaining skills to solve challenging problems involving graph-based malware propagation.

Statement

You’re given a network of nn nodes as an n×nn \times n adjacency matrix graph with the ithi^{th} node directly connected to the jthj^{th} node if graph[i][j] == 1.

A list of nodes, initial, is given, which contains nodes initially infected by malware. When two nodes are connected directly and at least one of them is infected by malware, both nodes will be infected by malware. This spread of malware will continue until every node in the connected component of nodes has been infected.

After the infection has stopped spreading, MM will represent the final number of nodes in the entire network that have been infected with malware.

Return a node from initial such that, when this node is removed from the graph, MM is minimized. If multiple nodes can be removed to minimize MM, return the node with the smallest index.

Note: If a node was removed from the initial list of infected nodes, it might still be infected later on due to the malware’s spread.

Constraints:

  • graph.length == graph[i].length
  • 22 \leq n 50\leq 50
  • graph[i][j] is 00 or 11.
  • graph[i][j] == graph[j][i]
  • graph[i][i] == 1
  • 11 \leq initial.length n\leq n
  • 00 \leq initial[i] n1\leq n - 1
  • All the integers in the initial are unique.