Leetcode Problem 863. All Nodes Distance K in Binary Tree

863. All Nodes Distance K in Binary Tree

Leetcode Solutions

Breadth-First Search on Equivalent Graph

  1. Create a helper function build_graph to construct the graph representation of the tree, connecting each node to its children and parent.
  2. Initialize a hash map graph to store the adjacency list of each node.
  3. Initialize a hash set visited to keep track of visited nodes during BFS.
  4. Initialize a queue queue for BFS, starting with the target node at distance 0.
  5. While the queue is not empty, process nodes in FIFO order, expanding to their unvisited neighbors and incrementing the distance.
  6. If the distance is equal to k, add the node's value to the result list.
  7. Continue BFS until all nodes at distance k are processed.
  8. Return the result list.
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Depth-First Search with Parent Pointers

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