Leetcode 261
https://leetcode.com/problems/graph-valid-tree/description/
You have a graph of n nodes labeled from 0 to n - 1. You are given an integer n and a list of edges where edges[i] = [ai, bi] indicates that there is an undirected edge between nodes ai and bi in the graph.
Return true if the edges of the given graph make up a valid tree, and false otherwise.
Example 1:
Input: n = 5, edges = [[0,1],[0,2],[0,3],[1,4]] Output: true Example 2:
Input: n = 5, edges = [[0,1],[1,2],[2,3],[1,3],[1,4]] Output: false
Constraints:
1 <= n <= 2000 0 <= edges.length <= 5000 edges[i].length == 2 0 <= ai, bi < n ai != bi There are no self-loops or repeated edges.