XOR & Single Number Problems in Java | Animated DSA #23

Bits III: The XOR Family — Single Number Problems in Java, explained with animated examples and worked code. Three properties, one whole class of problems, and O(1) space where a HashMap looked inevitable Lesson 23 of It’s Leo’s rebuilt DSA course. Practice alongside the examples and check the reasoning before moving on. CHAPTERS 00:00:00 XOR preserves parity of occurrences at every bit position 00:00:54 One unpaired value survives cancellation 00:01:47 Two single values leave one nonzero XOR difference 00:02:38 The differing bit can be the signed top position 00:03:29 Triples require counts modulo three, not parity 00:04:26 Two word-sized masks can encode counters modulo three 00:05:13 Missing-number XOR pairs values with a complete domain 00:06:06 A widened sum is also a correct missing-number method 00:06:55 XOR prefixes of consecutive nonnegative integers repeat by four 00:07:50 Array prefix XOR cancels a shared prefix without subtraction 00:08:44 Decode an XOR relation by applying the same partner again 00:09:40 An adder separates carryless sum from carried bits 00:10:26 Fixed width bounds carry propagation 00:11:22 Subset XOR totals have a counting argument 00:12:17 Use a reference that can expose a broken assumption #DSA #Java #Algorithms