#+PROPERTY: STUDY_DECK_02
* TODO 2924. Find Champion II :medium:
:PROPERTIES:
:NEETCODE: [[file:../../roadmap.org::*2924. Find Champion II][2924. Find Champion II]]
:END:

There are ~n~ teams numbered from ~0~ to ~n - 1~ in a tournament; each team is also a node in a *DAG*.

You are given the integer ~n~ and a *0-indexed* 2D integer array ~edges~ of length ~m~ representing the *DAG*, where ~edges[i] = [u_{i}, v_{i}]~ indicates that there is a directed edge from team ~u_{i}~ to team ~v_{i}~ in the graph.

A directed edge from ~a~ to ~b~ in the graph means that team ~a~ is *stronger* than team ~b~ and team ~b~ is *weaker* than team ~a~.

Team ~a~ will be the *champion* of the tournament if there is no team ~b~ that is *stronger* than team ~a~.

Return /the team that will be the *champion* of the tournament if there is a *unique* champion, otherwise, return /~-1~/./

*Notes*

 - A *cycle* is a series of nodes ~a_{1}, a_{2}, ..., a_{n}, a_{n+1}~ such that node ~a_{1}~ is the same node as node ~a_{n+1}~, the nodes ~a_{1}, a_{2}, ..., a_{n}~ are distinct, and there is a directed edge from the node ~a_{i}~ to node ~a_{i+1}~ for every ~i~ in the range ~[1, n]~.

 - A *DAG* is a directed graph that does not have any *cycle*.

*Example 1:*


#+begin_src
Input: n = 3, edges = [[0,1],[1,2]]
Output: 0
Explanation: Team 1 is weaker than team 0. Team 2 is weaker than team 1. So the champion is team 0.
#+end_src


*Example 2:*


#+begin_src
Input: n = 4, edges = [[0,2],[1,3],[1,2]]
Output: -1
Explanation: Team 2 is weaker than team 0 and team 1. Team 3 is weaker than team 1. But team 1 and team 0 are not weaker than any other teams. So the answer is -1.
#+end_src


*Constraints:*

 - ~1 <= n <= 100~

 - ~m == edges.length~

 - ~0 <= m <= n * (n - 1) / 2~

 - ~edges[i].length == 2~

 - ~0 <= edge[i][j] <= n - 1~

 - ~edges[i][0] != edges[i][1]~

 - The input is generated such that if team ~a~ is stronger than team ~b~, team ~b~ is not stronger than team ~a~.

 - The input is generated such that if team ~a~ is stronger than team ~b~ and team ~b~ is stronger than team ~c~, then team ~a~ is stronger than team ~c~.

** TODO Approach
Write your approach here.

** TODO Python
#+begin_src python
class Solution:
    def findChampion(self, n: int, edges: List[List[int]]) -> int:
#+end_src

** TODO C++
#+begin_src cpp
class Solution {
public:
    int findChampion(int n, vector<vector<int>>& edges) {
        
    }
};
#+end_src