You have a graph of `n` nodes. You are given an integer `n` and an array `edges` where `edges[i] = [ai, bi]` indicates that there is an edge between `ai` and `bi` in the graph.

Return _the number of connected components in the graph_.

Example 1:![](https://assets.leetcode.com/uploads/2021/03/14/conn1-graph.jpg)
    
    Input: n = 5, edges = [[0,1],[1,2],[3,4]] Output: 2 

Example 2:![](https://assets.leetcode.com/uploads/2021/03/14/conn2-graph.jpg)
    
    Input: n = 5, edges = [[0,1],[1,2],[2,3],[3,4]] Output: 1 

Constraints:

* `1 <= n <= 2000`
* `1 <= edges.length <= 5000`
* `edges[i].length == 2`
* `0 <= ai <= bi < n`
* `ai != bi`
* There are no repeated edges.

https://leetcode.com/problems/number-of-connected-components-in-an-undirected-graph/