1791. Find Center of Star Graph

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Graph

Time: O(1)

Space: O(1)

Intuition

The center node is connected to all other nodes. Find the node that appears in all edges.

Algorithm

1Center must appear in both edges[0] and edges[1]. Find common node.

Common Pitfalls

•With n>=3 nodes and n-1 edges in a star, center appears in every edge. Just check first two edges.

1791.cs

// Approach: Center node appears in both first two edges; compare endpoints directly.
// Time: O(1) Space: O(1)

public class Solution
{
    public int FindCenter(int[][] edges)
    {
        return (edges[0][0] == edges[1][0] || edges[0][0] == edges[1][1])
            ? edges[0][0]
            : edges[0][1];
    }
}

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