• ㊗️
• 大家
• offer
• 多多！

## Problem

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.

Example 1:

Input: nums1 = [1,7,11], nums2 = [2,4,6], k = 3
Output: [[1,2],[1,4],[1,6]]
Explanation: The first 3 pairs are returned from the sequence:
[1,2],[1,4],[1,6],[7,2],[7,4],[11,2],[7,6],[11,4],[11,6]


Example 2:

Input: nums1 = [1,1,2], nums2 = [1,2,3], k = 2
Output: [1,1],[1,1]
Explanation: The first 2 pairs are returned from the sequence:
[1,1],[1,1],[1,2],[2,1],[1,2],[2,2],[1,3],[1,3],[2,3]


Example 3:

Input: nums1 = [1,2], nums2 = [3], k = 3
Output: [1,3],[2,3]
Explanation: All possible pairs are returned from the sequence: [1,3],[2,3]


## Code

class Solution {
public List<List<Integer>> kSmallestPairs(int[] nums1, int[] nums2, int k) {
List<List<Integer>> res = new ArrayList<>();
if(nums1.length == 0 || nums2.length == 0 || k == 0) return res;

PriorityQueue<int[]> pq = new PriorityQueue<>((a, b) -> (a[0] + a[1] - b[0] - b[1]));

for(int i = 0; i < nums1.length && i < k; i++){
pq.offer(new int[]{nums1[i], nums2[0], 0});
}

while (!pq.isEmpty() && k-- > 0) {
int[] curr = pq.poll();