biweekly-51

Signed-off-by: ashKIK <[email protected]>

Author: px100

biweekly-51/ClosestRoom.java

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+import java.util.Arrays;
+import java.util.Comparator;
+import java.util.TreeSet;
+
+// https://leetcode.com/contest/biweekly-contest-51/problems/closest-room/
+
+public class ClosestRoom {
+
+  // We sort queries by the decreasing of its minSize order.
+  // We sort rooms by the decreasing of its size order.
+  // We initialize roomIdsSoFar TreeSet,
+  // this includes all room ids which have size >=minSize of current query so far.
+  // For each query:
+  //  - Add all room ids which have size >=minSize of current query.
+  //  - Query floor and ceiling of q[0] (preferredId) from roomIdsSoFar
+  //    to pick the id which closest to our preferredId
+
+  // online query processing
+  // floor and ceiling operate in O(logN)
+  // TC: O(NlogN + KlogK + KlogN)
+  // SC: O(N + K)
+  public int[] closestRoom(int[][] rooms, int[][] queries) {
+    Integer[] indices = new Integer[queries.length];
+    for (int i = 0; i < queries.length; i++) {
+      indices[i] = i;
+    }
+    // Sort by decreasing order of room size
+    Arrays.sort(rooms, Comparator.comparingInt(a -> a[1]));
+    // Sort by decreasing order of query minSize
+    Arrays.sort(indices, (a, b) -> Integer.compare(queries[b][1], queries[a][1]));
+    TreeSet<Integer> roomIdsSoFar = new TreeSet<>();
+    int[] result = new int[queries.length];
+    int id = 0;
+    for (int index : indices) {
+      // Add id of the room when its size >= query minSize
+      while (id < rooms.length && rooms[id][1] >= queries[index][1]) {
+        roomIdsSoFar.add(rooms[id++][0]);
+      }
+      result[index] = searchClosetRoomId(roomIdsSoFar, queries[index][0]);
+    }
+    return result;
+  }
+
+  private int searchClosetRoomId(TreeSet<Integer> roomIdsSoFar, int preferredId) {
+    Integer floor = roomIdsSoFar.floor(preferredId);
+    Integer ceiling = roomIdsSoFar.ceiling(preferredId);
+    int k = Integer.MAX_VALUE;
+    int closestRoomId = -1;
+    if (floor != null) {
+      closestRoomId = floor;
+      k = Math.abs(preferredId - floor);
+    }
+    if (ceiling != null) {
+      if (k > Math.abs(preferredId - ceiling)) {
+        closestRoomId = ceiling;
+      }
+    }
+    return closestRoomId;
+  }
+}

biweekly-51/MaximumElementAfterDecreasingAndRearranging.java

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+import java.util.Arrays;
+
+// https://leetcode.com/contest/biweekly-contest-51/problems/maximum-element-after-decreasing-and-rearranging/
+
+public class MaximumElementAfterDecreasingAndRearranging {
+
+  public int maximumElementAfterDecrementingAndRearranging(int[] arr) {
+    Arrays.sort(arr);
+    int cur = 0;
+    for (int v : arr) {
+      cur = Math.min(cur + 1, v);
+    }
+    return cur;
+  }
+}

biweekly-51/ReplaceAllDigitsWithCharacters.java

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+
+// https://leetcode.com/contest/biweekly-contest-51/problems/replace-all-digits-with-characters/
+
+public class ReplaceAllDigitsWithCharacters {
+
+  public String replaceDigits(String s) {
+    StringBuilder str = new StringBuilder(s.length());
+    for (int i = 0; i < s.length(); i++) {
+      str.append(i % 2 == 0 ? s.charAt(i) : shift(s, i));
+    }
+    return str.toString();
+  }
+
+  private char shift(String s, int idx) {
+    return (char) (s.charAt(idx - 1) + (s.charAt(idx) - '0'));
+  }
+}

biweekly-51/SeatReservationManager.java

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+import java.util.PriorityQueue;
+import java.util.Queue;
+
+// https://leetcode.com/contest/biweekly-contest-51/problems/seat-reservation-manager/
+
+public class SeatReservationManager {
+
+  class SeatManager {
+
+    private int count;
+    private final Queue<Integer> queue;
+
+    public SeatManager(int n) {
+      this.count = 1;
+      this.queue = new PriorityQueue<>();
+    }
+
+    public int reserve() {
+      if (queue.isEmpty()) {
+        return count++;
+      }
+      return queue.poll();
+    }
+
+    public void unreserve(int seatNumber) {
+      queue.offer(seatNumber);
+    }
+  }
+
+/**
+ * Your SeatManager object will be instantiated and called as such:
+ * SeatManager obj = new SeatManager(n);
+ * int param_1 = obj.reserve();
+ * obj.unreserve(seatNumber);
+ */
+}