Missing Number

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Problem

Given an array containing n distinct numbers taken from the range [0, n], return the one number in that range that is missing from the array.

Examples

Example 1

Input:nums = [3,0,1]

Output:2

Example 2

Input:nums = [9,6,4,2,3,5,7,0,1]

Output:8

Constraints

1 <= nums.length <= 10^4

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How to approach it: the Bit Manipulation pattern

Work directly on a number's binary representation using bitwise operators — often turning an O(n) or O(log n) problem into a handful of O(1) operations.

Look for this pattern when

The problem talks about bits directly (count set bits, reverse bits, single number among duplicates).
You want a constant-time trick instead of a loop for a numeric problem.

Read the full Bit Manipulation guide →

Video walkthroughs

Original problem on LeetCode ↗