KOPC12A  K12  Building Construction
Given N buildings of height h1,h2,h3...hn, the objective is to make every building has equal height. This can be done by removing bricks from a building or adding some bricks to a building.Removing a brick or adding a brick is done at certain cost which will be given along with the heights of the buildings.Find the minimal cost at which you can make the buildings look beautiful by reconstructing the buildings such that the N buildings satisfy
h1=h2=h3=..=hn=k ( k can be any number).
For convenience, all buildings are considered to be vertical piles of bricks, which are of same dimensions.
Input
The first line of input contains an integer T which denotes number of test cases .This will be followed by 3*T lines , 3 lines per test case. The first line of each test case contains an integer n and the second line contains n integers which denotes the heights of the buildings [h1,h2,h3....hn] and the third line contains n integers [c1,c2,c3...cn] which denotes the cost of adding or removing one unit of brick from the corresponding building.
T<=15;n<=10000;0<=Hi<=10000;0<=Ci<=10000;
Output
The output must contain T lines each line corresponding to a testcase.
Example
Input:
1 3 1 2 3 10 100 1000 Output:
120
hide comments
akarsh_raj:
20200522 08:21:24
someone please explain the example.


thanos_tapras:
20200306 23:03:28
Nice problem. Notes:


limon_88:
20191028 22:47:57
Must use long long int.. Last edit: 20191028 22:48:23 

rezagoodarzi:
20190725 11:05:14
badihi hast:) 

sepehragz1382:
20190725 06:36:33
1


surajgoel1225:
20190404 06:27:48
AC in one go . :)


devarshi09:
20190226 12:01:43
can anyone prove that the function is unimodal ? 

itsme_yoyo123:
20181210 20:31:48
I am using prefix sum but getting WA .Any hint or test case? 

divyansh_soni:
20181001 21:29:22
trivial upper and lower bound


soham_12345:
20180525 10:47:49
I don't understand how ternary search is applicable here! Can anyone give me proof that the function will be unimodal? Anyways better solution is possible. Hint: Prefix sums . Enjoy ;) 
Added by:  Radhakrishnan Venkataramani 
Date:  20120131 
Time limit:  1s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ASM64 
Resource:  Own 