The Runtime Theory
mediumLeetCode#bfs#tree-traversal

Binary Tree Right Side View

Return the value visible at the greatest depth when looking at the tree from the right.

The Runtime Theory Team25 min read
Solve it

Solving happens on the judge — come back and mark it done

Sample cases

inroot=[1,2,3,null,5,null,4]

out[1,3,4]

inroot=[1,null,3]

out[1,3]

inroot=[]

out[]

Return the value visible at the greatest depth when looking at the tree from the right.

A good solution should

  • State the invariant or decision rule that makes the approach correct.
  • Explain the time and space complexity in terms of the input sizes and required output.
  • Handle empty, minimal, duplicate, and boundary-shaped inputs covered by the contract.

Reasoning prompt

At each level select the last node in right-first BFS, or the first node in right-first DFS. Explain the traversal invariant.

Use the linked judge for the canonical problem. The examples above are compact TRT checks; write additional cases before submitting, especially for the boundary that tends to break your chosen invariant.

More practice in this topic

easy · treesBalanced Binary Treemedium · treesBinary Tree Level Order Traversalmedium · treesConstruct Binary Tree from Traversal

One dispatch a week

The trace behind each problem, the tradeoff that explains it, and one technical dispatch per week — no noise.

One technical dispatch per week. No noise.

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