Network Delay Time LeetCode solution in Java

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class Solution {
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  HashMap<Integer, HashMap<Integer, Integer>> map = new HashMap<>();
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  public int networkDelayTime(int[][] times, int n, int k) {
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    for (int i = 1; i <= n; i++) {
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      map.put(i, new HashMap<>());
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    }
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    for (int i = 0; i < times.length; i++) {
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      map.get(times[i][0]).put(times[i][1], times[i][2]);
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    }
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    int ans = BFS(k, n);
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    return ans == 1000 ? -1 : ans;
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  }
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  public int BFS(int k, int n) {
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    LinkedList<Integer> queue = new LinkedList<>();
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    int[] timeReach = new int[n + 1];
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    Arrays.fill(timeReach, 1000);
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    timeReach[0] = 0;
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    timeReach[k] = 0;
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    queue.add(k);
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    while (!queue.isEmpty()) {
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      int rv = queue.remove();
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      for (int nbrs : map.get(rv).keySet()) {
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        int t = map.get(rv).get(nbrs) + timeReach[rv];
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        if (t < timeReach[nbrs]) {
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          timeReach[nbrs] = t;
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          queue.add(nbrs);
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        }
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      }
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    }
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    int time = 0;
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    for (int i : timeReach) {
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      time = Math.max(i, time);
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    }
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    return time;
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  }
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}