Easy
Given an array nums containing n distinct numbers in the range [0, n], return the only number in the range that is missing from the array.
Example 1:
Input: nums = [3,0,1] Output: 2 Explanation: n = 3 since there are 3 numbers, so all numbers are in the range [0,3]. 2 is the missing number in the range since it does not appear in nums.
Example 2:
Input: nums = [0,1] Output: 2 Explanation: n = 2 since there are 2 numbers, so all numbers are in the range [0,2]. 2 is the missing number in the range since it does not appear in nums.
Example 3:
Input: nums = [9,6,4,2,3,5,7,0,1] Output: 8 Explanation: n = 9 since there are 9 numbers, so all numbers are in the range [0,9]. 8 is the missing number in the range since it does not appear in nums.
Constraints:
n == nums.length1 <= n <= 1040 <= nums[i] <= n- All the numbers of
numsare unique.
Follow up: Could you implement a solution using only O(1) extra space complexity and O(n) runtime complexity?
class Solution:
def missingNumber(self, nums: List[int]) -> int:
# s = set(nums)
# for n in range(len(nums)+1):
# if n not in s:
# return n
# nums.sort()
# for i in range(len(nums)):
# if i != nums[i]:
# return i
# return len(nums)
total = sum(nums)
expected_sum = len(nums)*(len(nums)+1)//2
return expected_sum - total