<p>In this problem, a tree is an <strong>undirected graph</strong> that is connected and has no cycles.</p>

<p>You are given a graph that started as a tree with <code>n</code> nodes labeled from <code>1</code> to <code>n</code>, with one additional edge added. The added edge has two <strong>different</strong> vertices chosen from <code>1</code> to <code>n</code>, and was not an edge that already existed. The graph is represented as an array <code>edges</code> of length <code>n</code> where <code>edges[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> indicates that there is an edge between nodes <code>a<sub>i</sub></code> and <code>b<sub>i</sub></code> in the graph.</p>

<p>Return <em>an edge that can be removed so that the resulting graph is a tree of </em><code>n</code><em> nodes</em>. If there are multiple answers, return the answer that occurs last in the input.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/05/02/reduntant1-1-graph.jpg" style="width: 222px; height: 222px;" />
<pre>
<strong>Input:</strong> edges = [[1,2],[1,3],[2,3]]
<strong>Output:</strong> [2,3]
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/05/02/reduntant1-2-graph.jpg" style="width: 382px; height: 222px;" />
<pre>
<strong>Input:</strong> edges = [[1,2],[2,3],[3,4],[1,4],[1,5]]
<strong>Output:</strong> [1,4]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>n == edges.length</code></li>
	<li><code>3 &lt;= n &lt;= 1000</code></li>
	<li><code>edges[i].length == 2</code></li>
	<li><code>1 &lt;= a<sub>i</sub> &lt; b<sub>i</sub> &lt;= edges.length</code></li>
	<li><code>a<sub>i</sub> != b<sub>i</sub></code></li>
	<li>There are no repeated edges.</li>
	<li>The given graph is connected.</li>
</ul>

class Solution {
public:
    int n; 
    vector<vector<int>> loop_edges;

    void print(vector<vector<int>>& v) {
        for (auto i: v) {
            for (auto j: i) cout<< j << " ";
            cout<<endl;
        }
    }

    bool in(vector<int>& edge) {
        for (auto i: loop_edges) {
            if (i[0] == edge[0] && i[1] == edge[1]) return true;
        }
        return false;
    }

    int dfs(vector<vector<int>>& adj, vector<bool>& vis, int s, int p) {
        vis[s] = true;
        for (auto i: adj[s]) {
            if (i == p) continue;
            if (vis[i] == true) {
                loop_edges.push_back(vector<int>{min(i, s), max(i, s)});
                return i;
            }
            auto k = dfs(adj, vis, i, s);
            if (k == i) return -1;
            if (k != -1) {
                loop_edges.push_back(vector<int>{min(i, s), max(i, s)});
                return k;
            }
        }

        return -1;
    }

    vector<int> findRedundantConnection(vector<vector<int>>& edges) {
        n = edges.size();
        vector<vector<int>> adj(n + 1);
        vector<bool> vis(n+1, false);

        for (auto i: edges) {
            adj[i[0]].push_back(i[1]);
            adj[i[1]].push_back(i[0]);
        }

        auto k = dfs(adj, vis, 1, -1);
        // print(ans);

        vector<int> res;
        for (auto i: edges) {
            if (in(i)) res = i;
        }

        return res;
    }
};
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