The Unpaired Value

Easy

In a warehouse every part is stored in pairs, except for one that lost its partner. You get an integer array values in which every value appears exactly twice, except for one value that appears exactly once. Return that lonely value. Aim for linear time and O(1) extra memory.

Example 1

values=[7, 3, 7] → 3

The 7 shows up twice, while the 3 shows up only once.

Example 2

values=[-5, 9, 0, 9, 0] → -5

Both 9 and 0 have a twin; -5 does not.

Example 3

values=[42] → 42

Constraints

1 ≤ len(values) ≤ 3·10⁴
-2³¹ ≤ values[i] ≤ 2³¹ - 1
Exactly one value appears once; every other value appears exactly twice

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Topics

Bit Manipulation Array

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Input

values=[7, 3, 7]

Expected

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