Description
You are given two arrays of positive integers, boxes and warehouse, representing the heights of some boxes of unit width and the heights of n rooms in a warehouse respectively. The warehouse's rooms are labelled from 0 to n - 1 from left to right where warehouse[i] (0-indexed) is the height of the ith room.
Boxes are put into the warehouse by the following rules:
- Boxes cannot be stacked.
- You can rearrange the insertion order of the boxes.
- Boxes can only be pushed into the warehouse from left to right only.
- If the height of some room in the warehouse is less than the height of a box, then that box and all other boxes behind it will be stopped before that room.
Return the maximum number of boxes you can put into the warehouse.
Example 1:
Input: boxes = [4,3,4,1], warehouse = [5,3,3,4,1] Output: 3 Explanation:We can first put the box of height 1 in room 4. Then we can put the box of height 3 in either of the 3 rooms 1, 2, or 3. Lastly, we can put one box of height 4 in room 0. There is no way we can fit all 4 boxes in the warehouse.
Example 2:
Input: boxes = [1,2,2,3,4], warehouse = [3,4,1,2] Output: 3 Explanation:Notice that it's not possible to put the box of height 4 into the warehouse since it cannot pass the first room of height 3. Also, for the last two rooms, 2 and 3, only boxes of height 1 can fit. We can fit 3 boxes maximum as shown above. The yellow box can also be put in room 2 instead. Swapping the orange and green boxes is also valid, or swapping one of them with the red box.
Example 3:
Input: boxes = [1,2,3], warehouse = [1,2,3,4] Output: 1 Explanation: Since the first room in the warehouse is of height 1, we can only put boxes of height 1.
Constraints:
n == warehouse.length1 <= boxes.length, warehouse.length <= 1051 <= boxes[i], warehouse[i] <= 109
Solutions
Solution 1
PythonJavaC++GoTypeScript
class Solution: def maxBoxesInWarehouse(self, boxes: List[int], warehouse: List[int]) -> int: n = len(warehouse) left = [warehouse[0]] * n for i in range(1, n): left[i] = min(left[i - 1], warehouse[i]) boxes.sort() i, j = 0, n - 1 while i < len(boxes): while j >= 0 and left[j] < boxes[i]: j -= 1 if j < 0: break i, j = i + 1, j - 1 return i(code-box)

We can first put the box of height 1 in room 4. Then we can put the box of height 3 in either of the 3 rooms 1, 2, or 3. Lastly, we can put one box of height 4 in room 0.
There is no way we can fit all 4 boxes in the warehouse.
Notice that it's not possible to put the box of height 4 into the warehouse since it cannot pass the first room of height 3.
Also, for the last two rooms, 2 and 3, only boxes of height 1 can fit.
We can fit 3 boxes maximum as shown above. The yellow box can also be put in room 2 instead.
Swapping the orange and green boxes is also valid, or swapping one of them with the red box.