1557. Minimum Number of Vertices to Reach All Nodes.cpp

class Solution {
public:
    vector<int> findSmallestSetOfVertices(int n, vector<vector<int>>& edges) {
        vector<int> indegree(n,0);
        for(auto& e:edges){
            indegree[e[1]]++;
        }
        vector<int> result;
        for(int i=0;i<n;++i)
            if(indegree[i]==0)
                result.push_back(i);
        return result;
    }
};