Build an n-ary tree from a forest

Question

i asked my professor to give me an old homework from another semester. And its about building a family tree and then finding the kinship between two nodes given. The family tree is about namekians (Dragon ball z) so every namekian has a single father.

The thing is that the input its something like this:

First name is the parent  Second name is the child
Iolin                     Lyre
Iolin                     Piyano
Batu                      Iolin
Batu                      Okiat
Ollusc                    Xylo
Organa                    Murd
Piccoro                   Ollusc
Piccoro                   Rombone
Rombone                   Organa

So i must have two trees, one with Piccoro as the leader (he is always the leader of one tree) and another with unknown leader.

The thing is that i have trouble when i try to create the trees, i know i have two roots, but as you can see the input is not in order so ill have nodes without parent until i read and create its parent. For example, i create Ollusc and its child Xylo, and then Organa and Murd, but i only have one root to represent that tree (Also i dont know if they are in the same tree or not) so i dont know how to "save" those nodes to connect them later, same happens with Organa and Rombone, Organa will be somewhere until i create Rombone and then connect him with Organa.

   Batu------>NULL
   /     \
 Iolin--->Okiat->NULL
  /   \
Lyre-->Piyano->NULL

   Piccoro-----> NULL
   /       \
 Ollusc--->Rombone->NULL
 /          /
Xylo->NULL Organa->NULL
           /
          Murd->NULL

I thought about saving nodes into a Queue or maybe a Stack because i dont know how much nodes will be floating somewhere until i connect them, but save them into a queue and then what?, because when i think about my next step i don't know what to do. Maybe store a node into the queue until a node Parent appears, and then take that node from queue, but queue its FIFO and doesnt help too much i think, because what if i need to take the second node or maybe the third instead of the front one. So maybe store them into a aux list? I should add a node to a list,Queue,stack if they have no parent and they are not the root right? or should i add the root to the list,Queue,Stack? Because i'm using root to build the tree In the first Tree my root its Iolin until batu appears and i change it to batu In the second tree Root will be always Piccoro, but its a little difficult to build a tree starting with piccoro because i dont know his childs

What do you think? what should i do? Do you have better or other ideas?

int main(int argc, char const *argv[])
{
    FILE *fpInput,*fpOutput;

    fpInput = fopen("input.in","r");
    fpOutput = fopen("output.out","w");

    if ((fpInput == NULL)){ printf("Open File Error\n"); exit(1); }

        // To read a line of the file
        char *fpInputString;
        char *parentInput, *childInput;

        // Because i dont know the number of lines that comes next, read until a number is found
        // That number is the number of consult of kinship about namekians

        fpInputString = inputString(fpInput,5);
        while ((strlen(fpInputString) != 1) && (strlen(fpInputString) != 2) && (strlen(fpInputString) != 3))
        {           

            parentInput = strtok(fpInputString," ");
            childInput  = strtok(NULL,"\0");

            fpInputString = inputString(fpInput,5);
        }


    fclose(fpInput);
    fclose(fpOutput);
    return 0;
}

InputString Function reads a whole line from a file

tree.h

// Struct of a node
struct treeNode
{
    // Name
    char *name;

    // Pointers
    struct treeNode *parent;
    struct treeNode *firstChild;
    struct treeNode *nextSibling;
    struct treeNode *prevSibling;
};

I'll be very thankful if you help me, i know it can be hard to understand me or my code

But i really want to learn new things about coding, i don't know if this homework will be better if i do it in c++ because c doesn't have STL

Answer 1

Save input information with map.

Find the ancestor node.

Add child nodes to the ancestor node.

Don't build trees for a node if it is not a ancestral node.