SUMFOUR  4 values whose sum is 0
The SUM problem can be formulated as follows: given four lists A, B, C, D of integer values, compute how many quadruplet (a, b, c, d ) belongs to A x B x C x D are such that a + b + c + d = 0 . In the following, we assume that all lists have the same size n
Input
The first line of the input file contains the size of the lists n (this value can be as large as 4000). We then have n lines containing four integer values (with absolute value as large as 2^{28} ) that belong respectively to A, B, C and D .
(Edited: n <= 2500)
Output
Output should be printed on a single line.
Example
Input: 6 45 22 42 16 41 27 56 30 36 53 37 77 36 30 75 46 26 38 10 62 32 54 6 45 Output: 5
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kshitij tripathi:
20150630 14:47:43
Nice Question..don't use Long Long int !! :D 

Varun Gambhir:
20150623 21:11:15
Ordered map in c++ gives TLE and unordered gives AC(after some optimisations). Finally AC. :D Last edit: 20150623 21:11:36 

sameer makker:
20150620 18:20:15
Can anybody explain why unordered_map fails here ?


Dhruv Mullick:
20150620 16:01:50
Optimisations needed. 

Ayur Jain:
20150620 10:55:09
Passes in O(n^2logn). Don't use STLs. 

sujit yadav:
20150619 00:31:13
take 2 pointer array in pair stl ....learn a lot .. thanks !!! :) 

bsaha205:
20150616 22:13:57
can you tell the tenth case??


xxbloodysantaxx:
20150608 20:48:58
Time Limit is too strict will make you cry! 

kirakira:
20150608 04:53:20
damn i almost cry for not AC such "easy" problem :(


i_am_looser:
20150508 15:19:09
STL  took 5 minute to get AC : ) 
Added by:  Abhilash I 
Date:  20070206 
Time limit:  1.419s 
Source limit:  50000B 
Memory limit:  1536MB 
Cluster:  Cube (Intel G860) 
Languages:  All except: ERL JSRHINO NODEJS PERL6 VB.NET 
Resource:  South western 0506 