https://www.rik-kisnah.ai/tags/two-pointers/Recent content in Two Pointers on Rik Kisnah - BlogHugoenTue, 28 Nov 2017 09:00:00 -0800https://www.rik-kisnah.ai/teach/coding/linked-list-cycle/Tue, 28 Nov 2017 09:00:00 -0800https://www.rik-kisnah.ai/teach/coding/linked-list-cycle/Two runners on a track. If the track is a loop, the fast one laps the slow one. If it is a straight road, the fast one falls off the end. No memory needed.https://www.rik-kisnah.ai/teach/coding/container-with-most-water/Tue, 08 Nov 2016 09:00:00 -0800https://www.rik-kisnah.ai/teach/coding/container-with-most-water/Vertical walls of different heights. Pick two that hold the most water between them. Start with a finger at each end and always move the shorter wall inward. Same shape as sorted Two Sum, and the lesson is why the move is safe.https://www.rik-kisnah.ai/teach/coding/move-zeroes/Tue, 19 Jul 2016 09:00:00 -0700https://www.rik-kisnah.ai/teach/coding/move-zeroes/Push every zero to the end of the array without changing the order of everything else. One finger marks where the next non-zero belongs. That finger is the whole idea behind two pointers.https://www.rik-kisnah.ai/teach/coding/two-sum/Tue, 14 Jun 2016 09:00:00 -0700https://www.rik-kisnah.ai/teach/coding/two-sum/Find two numbers in a list that add up to a target. Unsorted list: remember what you have seen in a hash map. Sorted list: one finger at each end, walk them towards each other. Two tricks, one problem, and half of the array questions you will ever be asked.