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Program to find closest room from queries in Python
Suppose there is an array called rooms. where rooms[i] contains a pair [roomId_i, size_i] denotes a room whose id is roomId_i and size is size_i. All room numbers are distinct. We also have another array queries, where queries[j] contains a pair [preferred_j, minSize_j]. The answer to the jth query is the room number id of a room such that −
The room has size of at least minSize_j, and
|id - preferred_j| is minimized.
Now, if there is a tie in the absolute difference, then use the room with the smallest id. If there is no such room, return -1. So we have to find an array called answer whose length is same as queries, that contains the answer to the jth query.
So, if the input is like rooms = [[2,2],[1,2],[3,2]] queries = [[3,1],[3,3],[5,2]], then the output will be [3, -1, 3] because
For query [3,1]: The room 3 is the closest because |3 - 3| = 0, and its size of 2 is at least 1, so the answer is 3.
For query [3,3]: There are no rooms whose size is at least 3, so the answer is -1.
For query [5,2]: The room 3 is the closest because |3 - 5| = 2, and its size of 2 is at least 2, so the answer is 3.
To solve this, we will follow these steps −
sort rooms based on size, when size are same then based on room id
queries = a list of pairs (qid,size,i) for index i, and pair (qid, size) in queries
sort the queries in reverse order based on size, if sizes are same, then based on preferred, when both are same then based on index
ans := an array of size same as size of queries and fill with -1
X := a new list
for each (qid, size, i) in queries, do
while rooms and size of last item of rooms >= size, do
(idr, p) := deleted last element from rooms
sort X after inserting idr
if X is not empty, then
j := index where to insert qid to remain X sorted
if j is same as size of X , then
ans[i] := last element of X
otherwise when j is same as 0, then
ans[i] := X[0]
otherwise,
if X[j] - qid < qid - X[j-1], then
ans[i] := X[j]
otherwise,
ans[i] := X[j-1]
return ans
Example
Let us see the following implementation to get better understanding
import bisect
def solve(rooms, queries):
rooms.sort(key = lambda x: (x[1], x[0]))
queries = [(qid,size,i) for i, (qid, size) in enumerate(queries)]
queries.sort(key = lambda x: (x[1], x[0], x[2]), reverse = True)
ans = [-1] * len(queries)
X = []
for qid, size, i in queries:
while rooms and rooms[-1][1] >= size:
idr, _ = rooms.pop()
bisect.insort(X, idr)
if X:
j = bisect.bisect(X, qid)
if j == len(X):
ans[i] = X[-1]
elif j == 0:
ans[i] = X[0]
else:
if X[j] - qid < qid - X[j-1]:
ans[i] = X[j]
else:
ans[i] = X[j-1]
return ans
rooms = [[2,2],[1,2],[3,2]]
queries = [[3,1],[3,3],[5,2]]
print(solve(rooms, queries))Input
[[2,2],[1,2],[3,2]], [[3,1],[3,3],[5,2]]
Output
[3, -1, 3]
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