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 <= 100000
• edges.length == n - 1
• edges[i].length == 2
• 1 <= ui, vi <= n
• ui != vi
• The given edges represent a valid star graph.

Problem Summary #

There is an undirected star graph consisting of n nodes labeled from 1 to n. A star graph has 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 edges[i] = [ui, vi] indicates that there is an edge between nodes ui and vi. Find and return the center node of the star graph represented by edges.

Solution Approach #

• Find the common value in the first two elements of edges; that is the center node.

Code #

package leetcode

func findCenter(edges [][]int) int {
	if edges[0][0] == edges[1][0] || edges[0][0] == edges[1][1] {
		return edges[0][0]
	}
	return edges[0][1]
}