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Find the missing number

Coding problemEasyAsked in: Accenture, Coupa

A list holds every whole number from 1 to n except one, in any order, with no repeats. So the list has n - 1 numbers. Return the number that is missing.

The missing number can be 1, n or anything in between. An empty list means n is 1 and the missing number is 1.

Examples

Example 1
Input: nums = [3,1,4]
Output: 2
Example 2
Input: nums = [1,2,3]
Output: 4
n is 4 here, and 4 is the missing number.
Example 3
Input: nums = []
Output: 1

Constraints

  • n is between 1 and 500,000
  • Every number in the list is between 1 and n and appears once

Run checks the 3 examples. Submit also runs the hidden tests: edge cases, large inputs and a time limit.

Run your code to see the results here.

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