剑指Offer-40-最小的k个数

堆/优先队列

public int[] getLeastNumbers(int[] arr, int k) {
        int len = arr.length;
        int[] res = new int[k];
        if(k==0) return res;
        PriorityQueue<Integer> queue = new PriorityQueue<>(k, new Comparator<Integer>() {
            @Override
            public int compare(Integer o1, Integer o2) {
                return o2-o1;
            }
        });
        for (int i = 0; i < k; i++) {
            queue.offer(arr[i]);
        }
        for (int i = k; i < len; i++) {
            if (arr[i] < queue.peek()) {
                queue.poll();
                queue.offer(arr[i]);
            }
        }
        for (int i = 0; i < k; i++) {
            res[i] = queue.poll();
        }
        return res;
    }