373.Find K Pairs with Smallest Sums

1- Heap

https://leetcode.com/problems/find-k-pairs-with-smallest-sums/discuss/84551/

https://discuss.leetcode.com/topic/52948/share-my-thoughts-and-clean-java-code

class Solution {
    public List<int[]> kSmallestPairs(int[] nums1, int[] nums2, int k) {
        PriorityQueue<int[]> pQueue = new PriorityQueue<>((a, b) -> (a[0] + a[1] - b[0] - b[1]));
        List<int[]> ans = new ArrayList<>();
        if(nums1.length==0 || nums2.length==0 || k==0) 
            return ans;
        for(int i = 0; i < nums1.length && i < k; i++){
            pQueue.offer(new int[] {nums1[i], nums2[0], 0});
        }
        for(int i = 0; i < k && !pQueue.isEmpty(); i++){
            int[] cur = pQueue.poll();
            ans.add(new int[]{cur[0], cur[1]});
            if(cur[2] == nums2.length -1){
                continue;
            }
            pQueue.offer(new int[] {cur[0], nums2[cur[2] + 1], cur[2] + 1});
        }
        return ans;
    }
}