https://oj.leetcode.com/problems/triangle/
https://oj.leetcode.com/problems/pascals-triangle/
https://oj.leetcode.com/problems/pascals-triangle-ii/
https://oj.leetcode.com/problems/best-time-to-buy-and-sell-stock/
https://oj.leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/
https://oj.leetcode.com/problems/best-time-to-buy-and-sell-stock-iii/