Find Center of Star Graph

1791. Find Center of Star Graph

Easy

There is an undirected star graph consisting of n nodes labeled from 1 to n. A star graph is a graph where there is one center node and exactly n - 1 edges that connect the center node with every other node.

You are given a 2D integer array edges where each edges[i] = [u_i, v_i] indicates that there is an edge between the nodes u_i and v_i. Return the center of the given star graph.

Example 1:

• Input: edges = [[1,2],[2,3],[4,2]]
• Output: 2
• Explanation: As shown in the figure above, node 2 is connected to every other node, so 2 is the center.

Example 2:

• Input: edges = [[1,2],[5,1],[1,3],[1,4]]
• Output: 1

Constraints:

• 3 <= n <= 10⁵
• edges.length == n - 1
• edges[i].length == 2
• 1 <= u_i, v_i <= n
• u_i != v_i
• The given edges represent a valid star graph.

Solution:

class Solution {

    /**
     * @param Integer[][] $edges
     * @return Integer
     */
    function findCenter($edges) {
        return $edges[0][0] == $edges[1][0] || $edges[0][0] == $edges[1][1]
               ? $edges[0][0]
               : $edges[0][1];
    }
}

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