Question 2* Sum from two array

Question

Given two arbitrary arrays(with possible duplicate), pick one element from each of the array, find all pairs with the largest sum <= target.

Solution 1: binary search

TC: O(mlogm + nlogn + n logm), assume n is smaller

Solution 2: 相向而行的two pointer

step1 确定能用2pointer，相向

step2 initialzation of i，j position

TC: O(nlogn + mlogm + m+ n)

Solution 3 treeMap