1376

class Solution {
int ans = 0;
public:
    int numOfMinutes(int n, int headID, vector<int>& manager, vector<int>& informTime) {
        vector<vector<int>> g;
        g.resize(n);

        // Make graph.
        for(int i=0; i<n; i++)
            if(manager[i] != -1)
                g[manager[i]].push_back(i);

        // DFS traversal.
        dfs(headID, 0, g, informTime);
        return ans;
    }

    void dfs(int node, int time, vector<vector<int>> &g, vector<int> &informTime){
        ans = max(ans, time);
        for(int child: g[node])
            dfs(child, time+informTime[node], g, informTime);
    }
};