Write an algorithm/code in C to do integer multiplication and division without using multiplication nor division operators. Do the same thing for partitioned algorithm/parallelizable (suitable in parallel processing)

Question

Write an algorithm/code in C to do integer multiplication and division without using multiplication nor division operators.  Do the same thing for partitioned algorithm/parallelizable (suitable in parallel processing)

Anónimo · Accepted Answer

The simplest way: int c = a*b c = 0; if ((a==0) || (b == 0) c = 0; if (a==1) c = b; else if (b==1) |c = a else for(i=0; i> 1; for(i=0; i>1); if (y % 2 == 0) return z<<1; else { return x + (z<<1); } } THere are other methods, though. Anybody can answer?

Caribou · Answer

Stackoverflow has a good description of algorithm.  Below is the python code. I am assuming  32 bit integers

powersof2=[2**i for i in range(32)]


def multiply(a,b):

    result=0
    for j in range(32):
        if (powersof2[j] & b):
            print  powersof2[j] & b
            result += (a << j)

    return result


def divide(a,b):

    result = 0

    for j in range(16,-1,-1):
        if (b << j) <= a:
            result += powersof2[j]
            a -= (b << j)
            print a

    return result

Dinesh Damaraju · Answer

Not a C Guy, but if in Java, you can do it as a method that returns for mutiplcation
return Math.pow(10, Math.log10(a)+Math.log10(b))
division:
return Math.pow(10, Math.log10(a)-Math.log10(b))

where a and b are the numbers

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