19 Subset.java Medium Java [Array, BFS, Backtracking, Bit Manipulation, DFS] 20 Subsets II.java Medium Java [Array, BFS, Backtracking, DFS] 21 Max Sum of Rectangle No Larger Than K.java Hard Java ...
1. Separate negative and positive numbeqrs. 2. Square all elements. 3. Reverse the squared negative list. 4. Merge both sorted lists using two pointers.