刷题记录贴

https://leetcode.com/problems/lo ... easing-subsequence/
没啥说的 小dp题 记住之前一位的结果和max值 走一遍算完

https://leetcode.com/problems/best-time-to-buy-and-sell-stock/
iterate vector, memorize smallest value so far, 每个点位和最小值的差值就是那一天买卖的最大收益, 始终存最大值即可

https://leetcode.com/problems/bi ... al-order-traversal/
BFS, 以root的col为0，BFS过程中记录column和node的pair instead of node only