leetcode/Problems/1443.cpp at master · DimitrijeDobrota/leetcode · GitHub

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class Solution {
  public:
    int minTime(int n, vector<vector<int>> &edges, vector<bool> &hasApple) {
        vector<vector<int>> adj(n, vector<int>());
        for (auto &e : edges) {
            adj[e[0]].push_back(e[1]);
            adj[e[1]].push_back(e[0]);
        }

        stack<pair<int, int>> st;
        int res = 0;

        st.push({0, -1});
        while (!st.empty()) {
            if (st.top().first == -1) {
                st.pop();

                auto [crnt, par] = st.top();
                st.pop();
                int count = 0;

                for (int c : adj[crnt]) {
                    if (c == par) continue;
                    count += hasApple[c];
                }

                res += count;
                hasApple[crnt] = hasApple[crnt] || count;
                continue;
            }

            auto [crnt, par] = st.top();
            st.push({-1, -1});

            for (int c : adj[crnt]) {
                if (c == par) continue;
                st.push({c, crnt});
            }
        }

        return res * 2;
    }
};