c++ : cycle formation using two vectors

Question

I have two vectors a and b of type std::vector<std::bitset<4> >

vector a --> 1st column vector b --> 2nd column

I want to form cycles using these 2 vectors

a[0] == b[0] == 0000 -- > no need to form a cycle

a[1] != b[1] --> cycle can be formed.

cycle 'c' is formed as follows: c = {a[1]==0001,b[1]==1000,...

then search for b[1] =1000 in `vector a` and add the corresponding value in b at that position

like now b[1] =1000 is at a[8], hence b[8] = 0100 is added to the cycle c = {a[1]=0001,b[1]=1000,b[8]=0100,...}

now b[8] = 0100 is at a[4], hence b[4] = 0010 is added to the cycle c= {a[1]=0001,b[1]=1000,b[8]=0100,b[4]=0010,..}

now b[4] =0010 is at a[2], hence b[2] == 0001 but b[2] = 0001 == 1st element in cycle 'c' hence leave it and this completes the cycle.

The below code is where I create a vector v1 to form the cycle 'c' , push values into it, perform operations and return the vector or cycle c.

x=a.at(i), y=b.at(i)

example : x=a.at(1),y=b.at(1)

std::vector<std::bitset<4> > getvector(int x, int y,const std::vector<std::bitset<4> >& a,const std::vector<std::bitset<4> >& b ) {
std::vector<std::bitset<4>> resultvector;
    resultvector.push_back(x);//push a.at(1) into r 
    resultvector.push_back(y);//push b.at(1) into r 
    while(resultvector.back()!=resultvector.front()) //run the loop until last element in vector r != first element in r and comes out when == 
    {

        //loop begin
        int pos = find(a,y);
        r.push_back(b.at(pos));
        //loop end 
    }
    return resultvector;
}

I want to know how to write this loop to perform the above operation.

I have given an example for my explanation.It would be clear now — user3898956
may be you should start by explaining the original problem and then explaining you vector solution — arash kordi
can any one help me with how to write loop to form this cycle — user3898956

Werner Erasmus Werner Erasmus · Accepted Answer · 2014-09-07T08:24:02

r is empty to begin with, therefore front/back may not be called. Your code and explanations make no sense.

Try to explain what you want to do without code, then think about loops and invariants.

Also, give your function an appropriate name. getVector is too general, and does not indicate your intent. The resultant vector is a function of the input, and the name must indicated in which way. Then we would be better able to help you.

c++ : cycle formation using two vectors

1 Answers