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Tested Python solution for LeetCode 665 with 17 pytest cases. Generate a practice environment with lcpy.
lcpy gen -n 665 # by problem number
lcpy gen -s non_decreasing_array # by problem name
nums with n integers, your task is to check if it could become non-decreasing by modifying at most one element.
We define an array is non-decreasing if nums[i] <= nums[i + 1] holds for every i (0-based) such that (0 <= i <= n - 2).
Input: nums = [4,2,3]
Output: true
Explanation: You could modify the first 4 to 1 to get a non-decreasing array.
Input: nums = [4,2,1]
Output: false
Explanation: You cannot get a non-decreasing array by modifying at most one element.
class Solution:
# Time: O(n)
# Space: O(1)
def check_possibility(self, nums: list[int]) -> bool:
changed = False
for i in range(len(nums) - 1):
if nums[i] <= nums[i + 1]:
continue
if changed:
return False
changed = True
if i == 0 or nums[i - 1] <= nums[i + 1]:
nums[i] = nums[i + 1]
else:
nums[i + 1] = nums[i]
return True
| Time | Space |
|---|---|
| O(n) | O(1) |