g1701_1800.s1791_find_center_of_star_graph.Solution Maven / Gradle / Ivy

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package g1701_1800.s1791_find_center_of_star_graph;

// #Easy #Graph #2022_05_03_Time_0_ms_(100.00%)_Space_71_MB_(77.85%)

/**
 * 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:**
 *
 * ![](https://assets.leetcode.com/uploads/2021/02/24/star_graph.png)
 *
 * **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.
**/
public 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];
    }
}