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Java-based LeetCode algorithm problem solutions, regularly updated
684\. Redundant Connection
Medium
In this problem, a tree is an **undirected graph** that is connected and has no cycles.
You are given a graph that started as a tree with `n` nodes labeled from `1` to `n`, with one additional edge added. The added edge has two **different** vertices chosen from `1` to `n`, and was not an edge that already existed. The graph is represented as an array `edges` of length `n` where edges[i] = [ai, bi]
indicates that there is an edge between nodes ai
and bi
in the graph.
Return _an edge that can be removed so that the resulting graph is a tree of_ `n` _nodes_. If there are multiple answers, return the answer that occurs last in the input.
**Example 1:**
![](https://assets.leetcode.com/uploads/2021/05/02/reduntant1-1-graph.jpg)
**Input:** edges = [[1,2],[1,3],[2,3]]
**Output:** [2,3]
**Example 2:**
![](https://assets.leetcode.com/uploads/2021/05/02/reduntant1-2-graph.jpg)
**Input:** edges = [[1,2],[2,3],[3,4],[1,4],[1,5]]
**Output:** [1,4]
**Constraints:**
* `n == edges.length`
* `3 <= n <= 1000`
* `edges[i].length == 2`
* 1 <= ai < bi <= edges.length
* ai != bi
* There are no repeated edges.
* The given graph is connected.