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respectable
Given two sequences of integers, count the minimum number of swaps (A[k], B[k]) needed to make both sequences increasing.
Programming language:

You have two sequences A and B consisting of integers, both of length N, and you would like them to be (strictly) increasing, i.e. for each K (0 ≤ K < N − 1), A[K] < A[K + 1] and B[K] < B[K + 1]. Thus, you need to modify the sequences, but the only manipulation you can perform is to swap an arbitrary element in sequence A with the corresponding element in sequence B. That is, both elements to be exchanged must occupy the same index position within each sequence.

For example, given A = [5, 3, 7, 7, 10] and B = [1, 6, 6, 9, 9], you can swap elements at positions 1 and 3, obtaining A = [5, 6, 7, 9, 10], B = [1, 3, 6, 7, 9].

Your goal is make both sequences increasing, using the smallest number of moves.

Write a function:

class Solution { public int solution(int[] A, int[] B); }

that, given two arrays A, B of length N, containing integers, returns the minimum number of swapping operations required to make the given arrays increasing. If it is impossible to achieve the goal, return −1.

For example, given:

A[0] = 5 B[0] = 1 A[1] = 3 B[1] = 6 A[2] = 7 B[2] = 6 A[3] = 7 B[3] = 9 A[4] = 10 B[4] = 9

your function should return 2, as explained above.

Given:

A[0] = 5 B[0] = 2 A[1] = -3 B[1] = 6 A[2] = 6 B[2] = -5 A[3] = 4 B[3] = 1 A[4] = 8 B[4] = 0

your function should return −1, since you cannot perform operations that would make the sequences become increasing.

Given:

A[0] = 1 B[0] = -2 A[1] = 5 B[1] = 0 A[2] = 6 B[2] = 2

your function should return 0, since the sequences are already increasing.

Write an efficient algorithm for the following assumptions:

  • N is an integer within the range [2..100,000];
  • each element of arrays A, B is an integer within the range [−1,000,000,000..1,000,000,000];
  • A and B have equal lengths.
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