[LeetCode] Divide Two Integers

Divide two integers without using multiplication, division and mod operator.

class Solution {
private:
    long long f[100];
public:
    int bsearch(long long a[], int left, int right, long long key)
    {
        if (left > right)
            return -1;
            
        int mid = left + (right - left) / 2;
        if (a[mid] == key)
            return mid;
        else if (a[mid] < key)
        {
            int pos = bsearch(a, mid + 1, right, key);
            return pos == -1 ? mid : pos;
        }
        else
        {
            return bsearch(a, left, mid - 1, key);
        }
    }
    
    int divide(int dividend, int divisor) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        int sign = dividend < 0 ? -1 : 1;
        if (divisor < 0)
            sign *= -1;
        
        long long div = dividend;
        div = abs(div);
        long long divisorL = divisor;
        divisorL = abs(divisorL);
        f[0] = divisorL;
        int size = 1;
        while(true)
        {
            if (f[size-1] >= div)
                break;
            f[size] = f[size-1] + f[size-1];
            size++;
        }
        
        int num = 0;
        long long sum = 0;
        while(div > 0)
        {
            int pos = bsearch(f, 0, size - 1, div);
            if (pos == -1)
                break;
            div -= f[pos];
            num += (1 << pos);
        }
                
        return num * sign;
    }
};