| English | 简体中文 |

# 684. Redundant Connection

## Description

In this problem, a tree is an **undirected** graph that is connected and has no cycles.

The given input is a graph that started as a tree with N nodes (with distinct values 1, 2, ..., 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 resulting graph is given as a 2D-array of `edges`

. Each element of `edges`

is a pair `[u, v]`

with `u < v`

, that represents an **undirected** edge connecting nodes `u`

and `v`

.

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 given 2D-array. The answer edge `[u, v]`

should be in the same format, with `u < v`

.

**Example 1:**

Input:[[1,2], [1,3], [2,3]]Output:[2,3]Explanation:The given undirected graph will be like this: 1 / \ 2 - 3

**Example 2:**

Input:[[1,2], [2,3], [3,4], [1,4], [1,5]]Output:[1,4]Explanation:The given undirected graph will be like this: 5 - 1 - 2 | | 4 - 3

**Note:**

**Update (2017-09-26):**

We have overhauled the problem description + test cases and specified clearly the graph is an ** undirected** graph. For the

**graph follow up please see**

*directed***Redundant Connection II**). We apologize for any inconvenience caused.