Lu, Yukuan

Given an integer n, return the number of trailing zeroes in n!.

Note that n! = n * (n - 1) * (n - 2) * ... * 3 * 2 * 1.

172. Factorial Trailing Zeroes

Ref: labuladong 题解

There are n gas stations along a circular route, where the amount of gas at the ith station is gas[i].

You have a car with an unlimited gas tank and it costs cost[i] of gas to travel from the ith station to its next (i + 1)th station. You begin the journey with an empty tank at one of the gas stations.

Given two integer arrays gas and cost, return the starting gas station's index if you can travel around the circuit once in the clockwise direction, otherwise return -1. If there exists a solution, it is guaranteed to be unique

134. Gas Station

Ref: Bernard Kolman, Robert C. Busby & Sharon Cutler Ros. (2014). Relations and Digraph. Discrete Mathematical Structures (6th ed., pp. 139-204). Pearson.

Ref: Bernard Kolman, Robert C. Busby & Sharon Cutler Ros. (2014). Relations and Digraph. Discrete Mathematical Structures (6th ed., pp. 139-204). Pearson.

Tricks when manipulating coordinates in algorithms.

You are given an integer array prices where prices[i] is the price of a given stock on the ith day, and an integer k.

Find the maximum profit you can achieve. You may complete at most k transactions: i.e. you may buy at most k times and sell at most k times.

Note: You may not engage in multiple transactions simultaneously (i.e., you must sell the stock before you buy again).

• 121. Best Time to Buy and Sell Stock
• 122. Best Time to Buy and Sell Stock II
• 123. Best Time to Buy and Sell Stock III
• 188. Best Time to Buy and Sell Stock IV

Sources:

1. Bernard Kolman, Robert C. Busby & Sharon Cutler Ros. (2014). Relations and Digraph. Discrete Mathematical Structures (6th ed., pp. 139-204). Pearson.

How to use Junit5, the java testing framework.

A special type of relation called "tree" in Discrete Mathematics.

Ref: Discrete Mathematical Structures, Sixth Edition, Bernard Kolman, Robert C. Busby, Sharon Cutler Ross.

Common binary tree algorithms from leetcode.