CODE 104: Divide Two Integers

public int divide(int dividend, int divisor) {
// IMPORTANT: Please reset any member data you declared, as
// the same Solution instance will be reused for each test case.
if (divisor == 1) {
return dividend;
} else if (divisor == -1) {
return -dividend;
} else if (Math.abs(divisor) == 2) {
int number = dividend >> 1;
if (divisor < 0) {
return -number;
}
return number;
}
long ldividend = 0L;
long ldivisor = 0L;
boolean isDividendFuShu = false;
boolean isDivisorFuShu = false;
if (divisor < 0) {
isDivisorFuShu = true;
ldivisor = Math.abs((long) divisor);
} else {
ldivisor = divisor;
}
if (dividend < 0) {
isDividendFuShu = true;
ldividend = Math.abs((long) dividend);
} else {
ldividend = dividend;
}
long start = 0l;
long end = ldividend;
while (start < end - 1) {
long mid = start + (end - start) / 2;
long tmpNumber = add(mid, ldivisor);
if (tmpNumber < ldividend) {
start = mid;
} else if (tmpNumber > ldividend) {
end = mid;
} else {
if ((isDividendFuShu && !isDivisorFuShu)
|| (!isDividendFuShu && isDivisorFuShu)) {
return -(int) mid;
} else {
return (int) mid;
}
}
}

if ((isDividendFuShu && !isDivisorFuShu)
|| (!isDividendFuShu && isDivisorFuShu)) {
return -(int) start;
} else {
return (int) start;
}
}

long add(long p, long num) {
if (0 == p) {
return 0;
}
long tmp = add(p >> 1, num) << 1;
if ((p & 1) != 0) {
tmp += num;
}
return tmp;
}