Swap Two Integers Without Extra Storage

Use either arithmetic or XOR to swap i and j without a temporary variable.

Try your own values

i j

Arithmetic XOR

Current values

Start

Step 0 / 3

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Operation

Initial state

We want i = 9 and j = 5 without creating a temporary variable.

The pattern

i = i + j j = i - j i = i - j

i = i ^ j j = i ^ j i = i ^ j

Idea: first store both original values inside i. The next two subtraction steps recover them in reverse order.

Interview answer i = i + j j = i - j i = i - j

Or, for integers, use XOR to avoid arithmetic overflow: i ^= j; j ^= i; i ^= j;