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class Solution {
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  public int smallestChair(int[][] times, int targetFriend) {
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    int targetStart = times[targetFriend][0];
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    Arrays.sort(times, (a, b) -> a[0] - b[0]);
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    PriorityQueue<Integer> available = new PriorityQueue<>();
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    for (int i = 0; i < times.length; ++i) {
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      available.offer(i);
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    }
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    PriorityQueue<int[]> pq = new PriorityQueue<>((a, b) -> a[0] - b[0]);
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    for (int i = 0; i < times.length; ++i) {
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      while (!pq.isEmpty() && pq.peek()[0] <= times[i][0]) {
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        available.offer(pq.poll()[1]);
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      }
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      if (times[i][0] == targetStart) {
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        break;
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      }
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      pq.offer(new int[] {times[i][1], available.poll()});
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    }
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    return available.peek();
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  }
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}