xmind: update Algorithms and survey about machine learning
leetcode: simple bfs to bt level traversal
leetcode: bt postorder traversal
-leetcode: container with most water. linear method.
leetcode: generate parentheses
leetcode: minimum-path-sum, in-place algorithm.
leetcode: remove dup from sorted array, use count
leetcode: spiral matrix ii, somewhat hard, but if your logic is right, it could be solved quickly
leetcode: unique-paths.. same dp