WEIRDFN - Weird Function

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Let us define:

  • F[1] = 1
  • F[i] = (a*M[i] + b*i + c)%1000000007 for i > 1

where M[i] is the median of the array {F[1], F[2], ..., F[i-1]}.

The median of an array is the middle element of that array when it is sorted. If there are an even number of elements in the array, we choose the first of the middle two elements to be the median.

Given a, b, c and n, calculate the sum F[1] + F[2] + .. + F[n].


The first line contains T the number of test cases. Each of the next T lines contain 4 integers : a, b, c and n.


Output T lines, one for each test case, containing the required sum.


1 <= T <= 100
0 <= a, b, c < 1000000007
1 <= n <= 200000


Sample Input:

1 0 0 3
3 1 2 6

Sample Output:


hide comments
Harpreet Singh: 2014-12-04 18:26:36

strict^strict timelimit

Kunal Behl: 2014-09-13 15:53:45

y time limit exceed everytime?? can anybody help please..

Matija Martiniæ: 2014-06-04 21:24:16

TLE even after using stl heap c++... :(
what to do now..??

(Tjandra Satria Gunawan)(曾毅昆): 2014-02-02 23:17:12

Time limit is too strict!

SaSukE: 2013-05-17 12:42:45

why implementation using red black tree is giving TLE ?? :/....Insertion and every query takes O(logn) still getting TLE ?? What should be the complexity of the solutn ??

Last edit: 2013-05-17 12:56:55
J.A.R.V.I.S.: 2013-02-03 13:36:52

Nice one :) solvable with STLs.. Watch out for overflows...

conioh: 2013-01-27 12:20:48

nice question...

Nilendu Das: 2012-12-09 20:07:18

Good question.. You can take help from RRATING problem from codechef..Jst the partition is diff..

Paul Draper: 2012-11-19 06:26:53

This problems "allows" for languages other than C/C++, but the time limit does not.

Anand: 2012-08-15 03:19:05

Very nice problem I am getting TLE

Added by:Varun Jalan
Time limit:1.116s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Resource:own problem used for Codechef Snackdown Onsite