hard
Find a pair (P, Q), such that A[P] <= A[Q] and the value Q - P is maximal.
100%
Correctness
100%
Performance
100%

A non-empty array A consisting of N integers is given.

A monotonic pair is a pair of integers (P, Q), such that 0 ≤ P ≤ Q < N and A[P] ≤ A[Q].

The goal is to find the monotonic pair whose indices are the furthest apart. More precisely, we should maximize the value Q − P. It is sufficient to find only the distance.

For example, consider array A such that:

A = 5 A = 3 A = 6 A = 3 A = 4 A = 2

There are eleven monotonic pairs: (0,0), (0, 2), (1, 1), (1, 2), (1, 3), (1, 4), (2, 2), (3, 3), (3, 4), (4, 4), (5, 5). The biggest distance is 3, in the pair (1, 4).

Write a function:

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

that, given a non-empty array A of N integers, returns the biggest distance within any of the monotonic pairs.

For example, given:

A = 5 A = 3 A = 6 A = 3 A = 4 A = 2

the function should return 3, as explained above.

Write an efficient algorithm for the following assumptions:

• N is an integer within the range [1..300,000];
• each element of array A is an integer within the range [−1,000,000,000..1,000,000,000].
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Solution
Programming language used Java
Total time used 2 minutes
Effective time used 2 minutes
Notes
not defined yet