941. Valid Mountain Array
Given an array of integers arr, return true if and only if it is a valid mountain array.
Recall that arr is a mountain array if and only if:
arr.length >= 3- There exists some
iwith0 < i < arr.length - 1such that:arr[0] < arr[1] < ... < arr[i - 1] < arr[i]arr[i] > arr[i + 1] > ... > arr[arr.length - 1]
Example 1:
Input: arr = [2,1] Output: false
Example 2:
Input: arr = [3,5,5] Output: false
Example 3:
Input: arr = [0,3,2,1] Output: true
Constraints:
1 <= arr.length <= 1040 <= arr[i] <= 104
IBM
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Hints open one at a time
Hint 1
It's very easy to keep track of a monotonically increasing or decreasing ordering of elements. You just need to be able to determine the start of the valley in the mountain and from that point onwards, it should be a valley i.e. no mini-hills after that. Use this information in regards to the values in the array and you will be able to come up with a straightforward solution.
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1class Solution:
2 def validMountainArray(self, arr: List[int]) -> bool:
3
Starter codePython 3Spaces: 4
Loading editor…
1class Solution:
2 def validMountainArray(self, arr: List[int]) -> bool:
3
Starter codePython 3Spaces: 4
Examples
Input
[2,1]
Input
[3,5,5]
Input
[0,3,2,1]
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