Find K Pairs with Smallest Sums

Statement

You are given two integer arrays, list1 and list2, sorted in non-decreasing order, and an integer, k.

A pair $(u, \space v)$ is defined as one element $u$ chosen from list1 and one element $v$ chosen from list2.

Your task is to return the k pairs $(u1,v1),(u2,v2),\mathrm{.}\mathrm{.}\mathrm{.}$ ...