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class Solution {
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  public int numOfMinutes(int n, int headID, int[] manager, int[] informTime) {
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    Map<Integer, List<Integer>> graph = new HashMap<>();
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    for (int i = 0; i < n; i++) {
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      graph.putIfAbsent(manager[i], new ArrayList<>());
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      graph.get(manager[i]).add(i);
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    }
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    return dfs(graph, headID, informTime);
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  }
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  int dfs(Map<Integer, List<Integer>> graph, int curHead, int[] informTime) {
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    int curMax = 0;
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    if (!graph.containsKey(curHead)) {
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      return curMax;
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    }
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    for (int subordinate : graph.get(curHead)) {
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      curMax = Math.max(curMax, dfs(graph, subordinate, informTime));
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    }
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    return curMax + informTime[curHead];
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  }
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}