21. 3SUM and APSP Hardness

MIT 6.890 Algorithmic Lower Bounds: Fun with Hardness Proofs, Fall 2014
Instructor: Erik Demaine

In this lecture, Professor Demaine explains hardness of problems that can be solved in polynomial time, but where that polynomial seems to be substantially superlinear.

License: Creative Commons BY-NC-SA

[johnniefujita]

let me ask something if at sorting step i don't discard the info about consecutive number and keep them maybe as set like the ones for quick find or something like... would the benefit of doin a single comparison for n sequential numbers benefit the overall time?? because i think we are dismissing information on the sorting phase. when we sort we can atest for the diff between to numbers and i think we are just keeping the simple greater or lesser value like normal sorting comparison. I am probably talking gibberish, but that got to me. that if a i had a kind of inner structure like that and a + b - c = rest c being the head of a set... i could just know that if a had a list of size rest c that the sum would be satisfied withou comparing them all. If anyone can review my answer i would be very happy.