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Tested Python solution for LeetCode 1228 with 16 pytest cases. Generate a practice environment with lcpy.
lcpy gen -n 1228 # by problem number
lcpy gen -s missing_number_in_arithmetic_progression # by problem name
arr, the values were in arithmetic progression: the values arr[i + 1] - arr[i] are all equal for every 0 <= i < arr.length - 1.
A value from arr was removed that was not the first or last value in the array.
Given arr, return the removed value.
Input: arr = [5,7,11,13]
Output: 9
Explanation: The previous array was [5,7,9,11,13].
Input: arr = [15,13,12]
Output: 14
Explanation: The previous array was [15,14,13,12].
class Solution:
# Time: O(n)
# Space: O(1)
def missing_number(self, arr: list[int]) -> int:
return (arr[0] + arr[-1]) * (len(arr) + 1) // 2 - sum(arr)
| Time | Space |
|---|---|
| O(n) | O(1) |