leetcode1228

 1 class Solution:
 2     def missingNumber(self, arr: 'List[int]') -> int:
 3         n = len(arr)
 4         common = (arr[n-1] - arr[0]) // n
 5         if common == 0:
 6             return 0
 7         for i in range(n):
 8             need = arr[0] + common * i
 9             if arr[i] != need:
10                 return need
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原文地址：https://www.cnblogs.com/asenyang/p/11711116.html