LeetCode: Find Center Of Star Graph Solution

Approach

Way 1: use hashmap to find the node which has edge to all others

Way 2: because there's only one center, check the first two

Implementation

1/**
2 * @param {number[][]} edges
3 * @return {number}
4 */
5var findCenter = function (edges) {
6  let map = new Map()
7  for (const [x, y] of edges) {
8    if (!map.has(x)) {
9      map.set(x, new Set())
10    }
11    if (!map.has(y)) {
12      map.set(y, new Set())
13    }
14    map.set(x, map.get(x).add(y))
15    map.set(y, map.get(y).add(x))
16  }
17
18  let res
19  let max = -Infinity
20  for (const [node, set] of map) {
21    if (set.size > max) {
22      res = node
23      max = set.size
24    }
25  }
26
27  return res
28}
29
30var findCenter = function (edges) {
31  return edges[0].filter(node => edges[1].includes(node))[0]
32}