1791. Find Center of Star Graph

Problem

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] = [ui, vi] indicates that there is an edge between the nodes ui and vi. 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 <= 10^5

• edges.length == n - 1

• edges[i].length == 2

• 1 <= ui, vi <= n

• ui != vi

• The given edges represent a valid star graph.

Solution (Java)

class Solution {
    public int findCenter(int[][] edges) {
        if (edges[0][0] == edges[1][0] || edges[0][0] == edges[1][1]) {
            return edges[0][0];
        }
        return edges[0][1];
    }
}

Explain:

nope.

Complexity:

• Time complexity : O(n).
• Space complexity : O(n).