1564. Put Boxes Into the Warehouse I

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.

class Solution {
public:
    int maxBoxesInWarehouse(vector<int>& boxes, vector<int>& warehouse) {
        for(int i = 1; i < warehouse.size(); i++) {
            if(warehouse[i] > warehouse[i - 1])
                warehouse[i] = warehouse[i - 1];
        }
        sort(boxes.begin(), boxes.end());
        int res = 0;
        for(int i = warehouse.size() - 1; i >= 0 and res < boxes.size(); i--) {
            if(warehouse[i] >= boxes[res])
                res++;
        }
        return res;
    }
};