✅ Bits (O(1) Space)
We just traverse all digits in all 3 numbers & use bit manipulation to check if every digit is between [1, 9].\n# C++\n    bool isFascinating(int n) {\n        
We just traverse all digits in all `3` numbers & use `bit manipulation` to check if every digit is between `[1, 9]`.\n# C++\n    bool isFascinating(int n) {\n        int freq = 0;\n        function<bool(int)> repd = [&](int n) {\n            while(n) {\n                int d = n % 10;\n                if(d == 0 || (freq >> d & 1)) return false;\n                freq |= (1 << d);\n                n /= 10;\n            }\n            return true;\n        };\n        return repd(n) and repd(2 * n) and repd(3 * n);\n    }\n
['Bit Manipulation', 'C']