Find Center of Star Graph

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 <= 105
• edges.length == n - 1
• edges[i].length == 2
• 1 <= ui, vi <= n
• ui != vi
• The given edges represent a valid star graph.

SOLUTION:

class Solution:
    def findCenter(self, edges: List[List[int]]) -> int:
        graph = {}
        for a, b in edges:
            if a in graph:
                graph[a][0] += 1
                graph[a][1] += 1
            else:
                graph[a] = [1, 1]
            if b in graph:
                graph[b][1] += 1
                graph[a][0] += 1
            else:
                graph[b] = [1, 1]
        k = len(graph) - 1
        for node in graph:
            if graph[node][1] == k:
                return node