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 <= 105edges.length == n - 1edges[i].length == 21 <= ui, vi <= nui != vi- The given
edgesrepresent a valid star graph.
struct Solution;
use std::collections::HashSet;
impl Solution {
fn find_center(edges: Vec<Vec<i32>>) -> i32 {
let mut hs: HashSet<i32> = HashSet::new();
for edge in edges {
let u = edge[0];
let v = edge[1];
if !hs.insert(u) {
return u;
}
if !hs.insert(v) {
return v;
}
}
0
}
}
#[test]
fn test() {
let edges = vec_vec_i32![[1, 2], [2, 3], [4, 2]];
let res = 2;
assert_eq!(Solution::find_center(edges), res);
let edges = vec_vec_i32![[1, 2], [5, 1], [1, 3], [1, 4]];
let res = 1;
assert_eq!(Solution::find_center(edges), res);
}