4 Values whose Sum is 0 poj-2785(四個長度爲4000的數組，從每一個數組中取出一個數，使取出的四個數和爲0 二分優化)

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 ) ∈ A x B x C x D are such that a + b + c + d = 0 . In the followin

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