CareerCup

Pretty simple solution, may not be the most efficient though

int bitCountDiff( byte x ) {
int count = 0;
do {
count += (x & 1) ;
x >>= 1;
}
while(x != 0);
return count;
}

Its an infinite loop for -1.

Typically we think that num >> 1 is same as num /2 and num << 1 is same as num *2. But thats not 100% true for -ve numbers. -1/2 is 0 but -1 >> 1 is still -1.

In Jimmy's code, replace x >>=1; to x /=2; should solve infinite loop for -ve numbers.

or you can read in an unsigned int

int i =42;
int cnt=0;
while(i!=0){
i = i & (i-1);
cnt++;
}

System.out.println(cnt); // =3 for i =42 = 0010 1010
Using Bit wise AND property.