Is a slice monotonic? A monotonic function is a single-variable function defined on some subset of real numbers, which is either non-decreasing everywhere (on its domain) or non-increasing everywhere. {1,7} - true {1,1} - true {3,3,1} - true {9,5,1} - true {23,5,23} - false

To determine if a slice is monotonic, you need to check whether it is either non-decreasing (each next element is not less than the previous one) or non-increasing (each next element is not greater than the previous one).

Example of a function in Go that checks the monotonicity of a slice of integers:

func isMonotonic(nums []int) bool {
    if len(nums) <= 1 {
        return true
    }

    increasing := true
    decreasing := true

    for i := 1; i < len(nums); i++ {
        if nums[i] > nums[i-1] {
            decreasing = false
        }
        if nums[i] < nums[i-1] {
            increasing = false
        }
    }

    return increasing || decreasing
}

Example usage:

fmt.Println(isMonotonic([]int{1,7}))       // true
fmt.Println(isMonotonic([]int{1,1}))       // true
fmt.Println(isMonotonic([]int{3,3,1}))     // true
fmt.Println(isMonotonic([]int{9,5,1}))     // true
fmt.Println(isMonotonic([]int{23,5,23}))   // false