How to Detect if Numbers Are in Order in Golang

The challenge

In this challenge, your function receives an array of integers as input. Your task is to determine whether the numbers are in ascending order. An array is said to be in ascending order if there are no two adjacent integers where the left integer exceeds the right integer in value.

For the purposes of this challenge, you may assume that all inputs are valid, i.e. non-empty arrays containing only integers.

Examples:

InAscOrder([]int{1, 2, 4, 7, 19}) // returns True
InAscOrder([]int{1, 2, 3, 4, 5}) // returns True
InAscOrder([]int{1, 6, 10, 18, 2, 4, 20}) // returns False
InAscOrder([]int{9, 8, 7, 6, 5, 4, 3, 2, 1}) // returns False because the numbers are in DESCENDING order

The solution in Golang

Option 1:

package solution

import "sort"

func InAscOrder(numbers []int) bool {
  return sort.IntsAreSorted(numbers)
}

Option 2:

package solution

func InAscOrder(numbers []int) bool {
  for i:=0; i < len(numbers) - 1; i++ {
    if(numbers[i] > numbers[i+1]) {
      return false
    }
  }
  return true
}

Option 3:

package solution

func InAscOrder(numbers []int) bool {
  i := 0
  for  ; i < len(numbers)-1 && numbers[i] <= numbers[i+1] ; i++ {}
  return i == len(numbers) - 1
}

Test cases to validate our solution

package our_test

import (
  . "github.com/onsi/ginkgo"
  . "github.com/onsi/gomega"
)

var _ = Describe("Test Example", func() {
  It("should test that the solution returns the correct value", func() {
    Expect(InAscOrder([]int{1, 2, 4, 7, 19})).To(Equal(true))
    Expect(InAscOrder([]int{1, 2, 3, 4, 5})).To(Equal(true))
    Expect(InAscOrder([]int{1, 6, 10, 18, 2, 4, 20})).To(Equal(false))
    Expect(InAscOrder([]int{9, 8, 7, 6, 5, 4, 3, 2, 1})).To(Equal(false))
  })
})