Missing Number

easyPROArrays & HashingNetflix DSA

Given an array containing n distinct numbers from 0, 1, 2, ..., n, find the one that is missing.

Example

Input

3,0,1

Output

Reasoning

Input: nums is $[3, 0, 1]$ , a list of distinct whole numbers. Its length is $n = 3$ , and that count fixes the range: the values are supposed to come from $\{0, 1, \dots, n\} = \{0, 1, 2, 3\}$ .
That range holds $n + 1 = 4$ candidates but the list only has $3$ entries, so exactly one candidate is absent.
Math: the answer is the single element of $\{0, 1, 2, 3\} \setminus \{3, 0, 1\}$ . Checking each candidate: $0$ is present, $1$ is present, $2$ is not, $3$ is present.
Output: the integer 2, a single number rather than a list, because there is only ever one gap.
Notice that $n$ is read from the list's length, not from its largest value. For $[0, 1]$ , $n = 2$ , so the range is $\{0, 1, 2\}$ and the missing value is 2, the top end itself, even though it is larger than every value in the list. The order of nums never affects the answer.

Constraints

1 <= n <= 10^4
0 <= nums[i] <= n
All numbers are unique

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solution.py

Python 3.13

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Missing Number

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