373. 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 (u 1,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]

# @lc code=start
using LeetCode
using DataStructures
function k_smallest_pairs(nums1::Vector{Int}, nums2::Vector{Int}, k::Int)
    hp = Tuple{Int, Int}[]
    odr = Base.Order.By(x -> -x[1] - x[2])
    for n1 in nums1, n2 in nums2
        heappush!(hp, (n1, n2), odr)
        length(hp) > k && heappop!(hp, odr)
    end
    sort!(hp; by = x -> x[1] + x[2])
end
# @lc code=end

k_smallest_pairs (generic function with 1 method)

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