Head of a gang

Head of a Gang

One way that the police finds the head of a gang is to check people’s phone calls. If there is a phone call between A and B, we say that A and B is related. The weight of a relation is defined to be the total time length of all the phone calls made between the two persons. A “Gang” is a cluster of more than 2 persons who are related to each other with total relation weight being greater than a given threthold K. In each gang, the one with maximum total weight is the head. Now given a list of phone calls, you are supposed to find the gangs and the heads.

Public Bike Management

1018 Public Bike Management

There is a public bike service in Hangzhou City which provides great convenience to the tourists from all over the world. One may rent a bike at any station and return it to any other stations in the city.

刷PAT的过程中遇到了两类排队问题,这里总结一下

• 所有人在同一时刻到达,如1014 Waiting in Line
• 每个人到达的时刻不同,如1017 Queueing at Bank)

Waiting in Line

1014 Waiting in Line

Suppose a bank has N windows open for service. There is a yellow line in front of the windows which devides the waiting area into two parts. The rules for the customers to wait in line are:

同学发过来一道有意思的题

For a given chemical formula represented by a string, count the number of atoms of each element contained in the molecule and return an object (associative array in PHP, Dictionary<string, int> in C#, Map<String,Integer> in Java).

Emergency

1003 Emergency

As an emergency rescue team leader of a city, you are given a special map of your country. The map shows several scattered cities connected by some roads. Amount of rescue teams in each city and the length of each road between any pair of cities are marked on the map. When there is an emergency call to you from some other city, your job is to lead your men to the place as quickly as possible, and at the mean time, call up as many hands on the way as possible.

Counting Leaves

1004 Counting Leaves

A family hierarchy is usually presented by a pedigree tree. Your job is to count those family members who have no child.

什么是异常

「现代操作系统」和国内的教材都没有讲清楚「中断、异常」这一组概念，再加上自己懒，一直没弄出个所以然，今天看了CSAPP上的解释，醍醐灌顶。