{"id":"power-of-four-subset-of-power-of-two","text":"The first two conditions in `isPowerOfFour` (`n > 0` and `n & (n-1) == 0`) are exactly the power-of-two check; the third condition (`n & 0x55555555 != 0`) narrows from powers-of-two to powers-of-four by requiring the set bit at an even position.","truth_value":"IN","source":"entries/2026/06/06/power-of-four-solution.md","source_url":"","source_hash":"","justifications":[],"dependents":[],"metadata":{},"created_at":"","updated_at":"","reviewed_at":"","verified_at":"","retracted_at":"","explanation":{"steps":[{"node":"power-of-four-subset-of-power-of-two","truth_value":"IN","reason":"premise"}]}}