997. Find the Town Judge

In a town, there are n people labeled from 1 to n. There is a rumor that one of these people is secretly the town judge.

If the town judge exists, then:

1. The town judge trusts nobody.
2. Everybody (except for the town judge) trusts the town judge.
3. There is exactly one person that satisfies properties 1 and 2.

You are given an array trust where trust[i] = [ai, bi] representing that the person labeled ai trusts the person labeled bi.

Return the label of the town judge if the town judge exists and can be identified, or return -1 otherwise.

class Solution {
public:
    int findJudge(int n, vector<vector<int>>& trust) {
        vector<int> adj(n+1,0), radj(n+1,0);
        for(auto& t : trust) {
            radj[t[0]]++;
            adj[t[1]]++;
        }
        for(int i = 1; i <= n; i++) {
            if(!radj[i] and adj[i] == n - 1)
                return i;
        }
        
        return -1;
    }
};