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1. Given a 2D matrix , with obstacles. Start from any of the first row, exit from any of the last row. What is the minimum steps?

           000001

           000100

           000000

           000100

     step

2. Given a list of buslines, and the stops of each busline, given a start stop, and a end stop, what is the minimum number of transfers to reach the end stop from start stop

815. Bus Routes

busline1: A B C D E F H

busline2: G D H E I

start:B

end:I

List<Buslines1, List<Stops>>   start, end

1. Find the start, List<Stops>

Map<Stop, Busline> invertedMap

busline1

                              / / / \ \ \ \

                           A B C D E F H

                                            \ \

                                            busline2

                                             / | \ \

invertedMap:  stop , list<buslines>

3. Given a table of candidates, each has a column of quality score, a minimum salary.

Also,  if you want to hire A and B both, you must pay A at least 10/5 * 20 = 40 instead of 15.

What is the minimum salary you have to pay in total to hire them all?

follow up. if you only want to hire k out of n candidates, what is the minimum salary you have to pay?

A: 1 , 1, 1

B: 5, 20, 4

C: 25, 20, 0.8

A: 1 , 1

B: 5，20

maxHeap: (n-k)logn

B：4 => A:4

ratio sort  4 1 0.8

quality score:    1 5 25

N choose k

4. Given a box of fixed width and height in pixels, and two APIs getWidth(char c, font), getHeight(char c). Given a string “abc...hi”, what is the maximum font size can you use?

paper width, height

paper fix size

xxxxxxx

xxxxxxx

xxxxxxx

binary search

a

b

c

h

i

0,

5. given a list of subsequence of certain original array, recover the original array.

e.g.[1, 3, 5, 9]    

    [3, 4, 9]

    [4,5]

Then the original array is :  [1, 3, 4, 5, 9]

if no unique solution, return null

1 : 3 , 5, 9

3 : 5, 9, 4

5 : 9

4 : 9, 5

444. Sequence Reconstruction