Problem · Array

Even-Position Monotonicity

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Problem statement

Given an array of non-negative integers numbers, inspect the values at zero-based even indices: numbers[0], numbers[2], numbers[4], and so on.

  • Return "increasing" if these values are in strictly increasing order.
  • Return "decreasing" if these values are in strictly decreasing order.
  • Return "none" if these values are not strictly monotonic.

Values at odd indices do not affect the result.

A solution with time complexity not worse than O(numbers.length^2) fits within the execution time limit.

Function

solution(numbers: int[]) → String

Examples

Example 1

numbers = [12,65,15,72,19,72]return = "increasing"

The values at even indices are 12, 15, and 19. Since 12 < 15 < 19, the result is "increasing".

Example 2

numbers = [12,1,54,5,19,14]return = "none"

The values at even indices are 12, 54, and 19. They first increase and then decrease, so the result is "none".

Example 3

numbers = [666,17,66,5,6,23]return = "decreasing"

The values at even indices are 666, 66, and 6. Since 666 > 66 > 6, the result is "decreasing".

Constraints

  • numbers.length >= 3.
  • Every numbers[i] is a non-negative integer that fits in a 32-bit signed integer.

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public String solution(int[] numbers) {
    // write your code here
}
numbers[12,65,15,72,19,72]
expected"increasing"
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