Given an array A of integers, find the index of values that satisfy
A + B = C + D, where
A,B,C & D are integers values in the array
1) Return the indices `A1 B1 C1 D1`, so that A[A1] + A[B1] = A[C1] + A[D1] A1 < B1, C1 < D1 A1 < C1, B1 != D1, B1 != C1 2) If there are more than one solutions, then return the tuple of values which are lexicographical smallest. Assume we have two solutions S1 : A1 B1 C1 D1 ( these are values of indices int the array ) S2 : A2 B2 C2 D2 S1 is lexicographically smaller than S2 iff A1 < A2 OR A1 = A2 AND B1 < B2 OR A1 = A2 AND B1 = B2 AND C1 < C2 OR A1 = A2 AND B1 = B2 AND C1 = C2 AND D1 < D2
Input: [3, 4, 7, 1, 2, 9, 8] Output: [0, 2, 3, 5] (O index)
If no solution is possible, return an empty list.