Java 几个傻瓜算法

public static int numberOfLeadingZeros(int i) {
        // HD, Figure 5-6
        if (i == 0)
            return 32;
        int n = 1;
        if (i >>> 16 == 0) { n += 16; i <<= 16; }
        if (i >>> 24 == 0) { n +=  8; i <<=  8; }
        if (i >>> 28 == 0) { n +=  4; i <<=  4; }
        if (i >>> 30 == 0) { n +=  2; i <<=  2; }
        n -= i >>> 31;
        return n;
    }

知道是啥意思么?返回第一个1之前的0的个数!




public static int numberOfTrailingZeros(int i) {
        // HD, Figure 5-14
 int y;
 if (i == 0) return 32;
 int n = 31;
 y = i <<16; if (y != 0) { n = n -16; i = y; }
 y = i << 8; if (y != 0) { n = n - 8; i = y; }
 y = i << 4; if (y != 0) { n = n - 4; i = y; }
 y = i << 2; if (y != 0) { n = n - 2; i = y; }
 return n - ((i << 1) >>> 31);
    }