Google 面经

1. 給你兩個string 
if function(s1) == function(s2)  return true
else return false. 1point3acres.com/bbs

function做的事情  遇到b 就刪除前面一個字元  其他就不管  當b太多的時候 return ""

for example 
accc =>  accc
accb => ac
abdd => dd
. visit 1point3acres.com for more.
如果string 非常大  
無法fit memory 怎麼辦
. 鐣欏鐢宠璁哄潧-涓€浜╀笁鍒嗗湴

答案:
用iterator  然後從後面開始讀

 

2. 给三个function
String hash(String s). 
String encrypt(String message)
String decrypt(String secret)

eg.
encrypt("secret") = "12345"
decrypt("12345") = "secret"
要设计一个信息加密serve，其实是写一个class 完成这两个function
void sendMessage(String id, String message). 
String getMessage(String id)

eg.
sendMessage('Bob', 'Hi')
getMessage('Bob') // 'Hi'

 

3. Robot Clearner

Givena robot cleaner in a room modeled as a grid. Each cell in the grid can be emptyor blocked. The robot cleaner can move forward, turn left or turn right. Whenit tries to move into a blocked cell, its bumper sensor detects the obstacleand it stays on the current cell.

 

Thecontrol API:

interfaceRobot {

  //returns true if next cell is open and robot moves into the cell.

  //returns false if next cell is obstacle and robot stays on the current cell.

  booleanMove();

 

  //Robot will stay on the same cell after calling Turn*. k indicates how

  //many turns to perform.

  voidTurnLeft(int k);

  voidTurnRight(int k);

 

  //Clean the current cell.

  voidClean();more.

  booleanMove(Direction d);

}

 

Sampleinput

++++++++++

+........+

+...^....+

+.+......+

++++.+++++

+.....+

+++++++

. 1point 3acres 璁哄潧

要求用给定的API打扫完所有empty格子。Timecomplexity, linear in term of room space.