Leetcode 685: redudant connection - discussion with the peer on January 17, 2018 10:00 PM

Leetcode 684 redudant connection

 /*
 Leetcode 
 1 - 2  -3 
 
     |   |
     4 - 5
     
     largest edge 
     
     
     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.


     
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            
    
 //////////////////////////
 What are the algorithms for graphes? Peer asked himself. 
 dijkstra
 belmanford
 topological sort
 Krusal algorithm (MST)   <-  Julia added
 dfs / bfs 
 
                   5
                /      \
            4             6
         /  |  \        / | \
        1   2   3  --  7  6  8
        
Julia shared the blogs to read:         
 https://en.wikipedia.org/wiki/Kruskal%27s_algorithm
      
 http://blog.csdn.net/dm_vincent/article/details/7655764