896. Monotonic Array

Easy

An array is monotonic if it is either monotone increasing or monotone decreasing.

An array nums is monotone increasing if for all i <= j, nums[i] <= nums[j]. An array nums is monotone decreasing if for all i <= j, nums[i] >= nums[j].

Given an integer array nums, return true if the given array is monotonic, or false otherwise.

Example 1:

Input: nums = [1,2,2,3]
Output:
 true

Example 2:

Input: nums = [6,5,4,4]
Output:
 true

Example 3:

Input: nums = [1,3,2]
Output:
 false

Constraints:

• 1 <= nums.length <= 105

• -105 <= nums[i] <= 105

解題

O(n)

Runtime: 152 ms, faster than 85.47%

Memory Usage: 9.2 MB, less than 77.78%

func isMonotonic(nums []int) bool {
    if len(nums)==1 { return true }
    
    for i:=1; i<len(nums); i++ {
        if nums[i]<nums[i-1] {
            for j:=i; j<len(nums); j++ {
                if nums[j]>nums[j-1] { return false }
            }
            break
        }
        
        if nums[i]>nums[i-1] {
            for j:=i; j<len(nums); j++ {
                if nums[j]<nums[j-1] { return false }
            }
            break
        }
    }
    
    return true
    
}