程式小試身手

cars=[2,10,8,17], k=3

這題我原本以為是排序後取三蓋屋頂，排序[2,8,10,17] ,2~10 得 10-2+1=9

結果還要考慮取最小間距 

cars=[1,7,9,10,11], k=3 ,1~9 得9-1+1=9 但實際應為 11-9+1=3

看到解答用PriorityQueue，很少用反而學習到，總之是把最小放最前,poll取最前並刪除

Collections.reverseOrder() 反轉，最大放最前

public static long carParkingRoof(List<Long> cars, int k) {
    // Write your code here
        if (cars.size() == 0 || k < 0) {
            return 0;
        }

        PriorityQueue<Long> maxHeap = new PriorityQueue<Long>(k, Collections.reverseOrder()); 

        long minSlot = Long.MAX_VALUE;

        for (long carSlot : cars) {
            maxHeap.offer(carSlot);
            
            minSlot = Math.min(minSlot, carSlot);

            if (maxHeap.size() > k) {
                maxHeap.poll();
            }
        }

        return maxHeap.poll() - minSlot + 1;
    }