Poison

231. Power of Two

发表于
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class Solution {
    public boolean isPowerOfTwo(int n) {
        if (n <= 0) {
            return false;
        }

        return Integer.bitCount(n) == 1;
    }
}
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class Solution {
    public boolean isPowerOfTwo(int n) {
        if (n <= 0) {
            return false;
        }

        return (n & (n - 1)) == 0;
    }
}
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class Solution {
    public boolean isPowerOfTwo(int n) {
        switch (n) {
            case 0b00000000_00000000_00000000_00000001:
            case 0b00000000_00000000_00000000_00000010:
            case 0b00000000_00000000_00000000_00000100:
            case 0b00000000_00000000_00000000_00001000:
            case 0b00000000_00000000_00000000_00010000:
            case 0b00000000_00000000_00000000_00100000:
            case 0b00000000_00000000_00000000_01000000:
            case 0b00000000_00000000_00000000_10000000:
            case 0b00000000_00000000_00000001_00000000:
            case 0b00000000_00000000_00000010_00000000:
            case 0b00000000_00000000_00000100_00000000:
            case 0b00000000_00000000_00001000_00000000:
            case 0b00000000_00000000_00010000_00000000:
            case 0b00000000_00000000_00100000_00000000:
            case 0b00000000_00000000_01000000_00000000:
            case 0b00000000_00000000_10000000_00000000:
            case 0b00000000_00000001_00000000_00000000:
            case 0b00000000_00000010_00000000_00000000:
            case 0b00000000_00000100_00000000_00000000:
            case 0b00000000_00001000_00000000_00000000:
            case 0b00000000_00010000_00000000_00000000:
            case 0b00000000_00100000_00000000_00000000:
            case 0b00000000_01000000_00000000_00000000:
            case 0b00000000_10000000_00000000_00000000:
            case 0b00000001_00000000_00000000_00000000:
            case 0b00000010_00000000_00000000_00000000:
            case 0b00000100_00000000_00000000_00000000:
            case 0b00001000_00000000_00000000_00000000:
            case 0b00010000_00000000_00000000_00000000:
            case 0b00100000_00000000_00000000_00000000:
            case 0b01000000_00000000_00000000_00000000:
                return true;
            default:
                return false;
        }
    }
}
Reference

231. Power of Two