【java】703. Kth Largest Element in a Stream

问题原文https://leetcode-cn.com/problems/kth-largest-element-in-a-stream/description/

这道题的技巧是在队列里面维护k个元素。

class KthLargest {
    int k;
    PriorityQueue<Integer> queue;
    public KthLargest(int k, int[] nums) {
        this.k  = k;
        queue = new PriorityQueue<>();
        if(nums.length <= k) {
            for(int ele:nums) queue.add(ele);
        }else {
            for(int i = 0;i<k;i++) queue.add(nums[i]);
            for(int i = k;i<nums.length;i++) {
                if(queue.peek()<nums[i]) {
                    queue.poll();
                    queue.add(nums[i]);
                }
            }
        }
    }

    public int add(int val) {
        if(queue.size()<k) {
            queue.offer(val);
        }else if(queue.peek()<val) {
            queue.poll();
            queue.offer(val);
        }
        return queue.peek();
    }
}