# LeetCode 1791. Find Center of Star Graph

## Description

https://leetcode.com/problems/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.

## Explanation

Find the vertice which occurs the same as the number of edges.

## Python Solution

``````class Solution:
def findCenter(self, edges: List[List[int]]) -> int:

counter = {}

for edge in edges:
counter[edge] = counter.get(edge, 0) + 1
counter[edge] = counter.get(edge, 0) + 1

for key, value in counter.items():
if value == len(edges):
return key
``````
• Time Complexity: O(N).
• Space Complexity: O(N).