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Problem: Minimize Malware Spread

Hard
40 min
Understand how to apply the Union Find algorithm to identify and remove a node infected by malware to minimize its spread across a connected network. Explore how malware propagates within connected components and practice implementing an efficient solution to reduce overall infections.

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

Hard
40 min
Understand how to apply the Union Find algorithm to identify and remove a node infected by malware to minimize its spread across a connected network. Explore how malware propagates within connected components and practice implementing an efficient solution to reduce overall infections.

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.