leetcode373. Find K Pairs with Smallest Sums

You are given two integer arrays nums1 and nums2 sorted in ascending order and an integer k.

Define a pair (u,v) which consists of one element from the first array and one element from the second array.

Find the k pairs (u1,v1),(u2,v2) ...(uk,vk) with the smallest sums.

    public List<int[]> kSmallestPairs(int[] nums1, int[] nums2, int k) {
        List<int[]> result = new ArrayList<int[]>();
        if(nums1.length == 0 || nums2.length == 0 || k == 0) return result;
        PriorityQueue<int[]> heap = new PriorityQueue<int[]>(new Comparator<int[]>(){

            @Override
            public int compare(int[] o1, int[] o2) {
                return o1[0] + o1[1] - o2[0] - o2[1];
            }});
        
        for(int i = 0 ; i<nums1.length ; i++){
            heap.offer(new int[]{nums1[i], nums2[0], 0});
        }
        while(k-- != 0 && !heap.isEmpty()) {
            int[] min = heap.poll();
            result.add(new int[]{min[0], min[1]});
            if(min[2] == nums2.length) continue;
            heap.offer(new int[]{min[0], nums2[min[2]+1], min[2] + 1});
        }
        return result;
        
    }