How do you solve Find Center of Star Graph on LeetCode?

Find Center of Star Graph (LeetCode #1791) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(1) time complexity and O(1) space complexity. Key insight: The center node is the only one connected to all other nodes.

What is the brute force solution for Find Center of Star Graph?

The brute force approach for Find Center of Star Graph is Brute Force, with O(n²) time complexity and O(n) space complexity. In a star graph, the center node is connected to all other nodes. A brute-force approach would involve checking each node to see how many edges it has. The node with the highest count is the center. The optimal Optimal Solution approach improves this to O(1).

What algorithm or data structure is used to solve Find Center of Star Graph?

Find Center of Star Graph uses the following concepts: Graph Theory. The recommended patterns to study are: Hash Map, Array.

What are the interview tips for Find Center of Star Graph?

Always clarify the structure of the graph before diving into coding. Think about edge cases, such as the minimum number of edges. Practice identifying patterns in graph-related problems.

What are common mistakes when solving Find Center of Star Graph?

Assuming all nodes have the same degree without checking. Not recognizing that the center is one of the nodes in the first two edges.

#1791

Find Center of Star Graph

Easy

Graph TheoryHash MapArray

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n²)	O(1)
Space	O(n)	O(1)

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Intuition

Time O(1)Space O(1)

In a star graph, the center node is directly connected to all other nodes. Thus, we can simply check the first two edges to determine the center, as it must be one of the nodes in those edges.

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Algorithm

2 steps

1Step 1: Return the first node of the first edge if it is also present in the second edge.
2Step 2: If not, return the second node of the first edge.

solution.py4 lines

1# Full working Python code
2
3def findCenter(edges):
4    return edges[0][0] if edges[0][0] in edges[1] else edges[0][1]

ℹ

Complexity note: The time complexity is O(1) because we only check the first two edges. The space complexity is O(1) since we do not use any additional data structures.

1The center node is the only one connected to all other nodes.
2Checking the first two edges is sufficient to find the center.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.