Introduction

In this blog post, we will explore how to solve the LeetCode problem "1791" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

Problem Statement

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

Here's the breakdown of the solution:

• Identify the Center: In a star graph, the center node is connected to all other nodes. This means the center node will appear in every edge.
• Check First Two Edges: By inspecting the first two edges, we can determine the center node. If the nodes in the first edge share a common node with the second edge, that common node must be the center.

• Return the Center: Once identified, return the center node.

• Runtime Complexity: O(1), Storage Complexity: O(1)

Code

    def find_center(edges: list[list[int]]) -> int:
    """
    Finds the center of a star graph given a list of edges.

    Args:
        edges: A list of edges, where each edge is a list of two integers representing the nodes connected by the edge.

    Returns:
        The center of the star graph.
    """
    if edges[0][0] == edges[1][0] or edges[0][0] == edges[1][1]:
        return edges[0][0]
    else:
        return edges[0][1]