What this function does(i tried to trace it

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transgalactic
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i understand what each line does here

but i can't see what this function does in general??

Code: 
typedef struct node node;         //node is alias for struct node
struct node{                               
    int value,count;
    node *lc,*rc;
};

node *what(node *tree){
    node *save,*temp;
    int flag;
    if(!tree)return NULL;          //if root is null the program stops and return null
    if(!tree->lc && !tree->rc){ 
           free(tree);
           return NULL;
    }                                         //if the sons of root is null then we free the root and 
                                               //return null


    save=temp=tree;                // save and temp point to the same place as the root
 
    if(save->lc) {flag=1;            //if (*save).lc differs null 

                   save=save->lc;    //save points to the same place as its left son
 
                   while(save->rc){ //while saves right son differs null
                       flag=0;        
                       temp=save;
                       save=save->rc;  //save point to the same place where save right son
                   }
    }
    else{ flag=0;               //if (*save).lc equals null 
           save=save->rc;    //save points to the same place as its right son
           while(save->lc){  //while saves left son differs null
               flag=0;
               temp=save;   
               save=save->rc; //save points to the same place as its right son
           }

    }
    if(!flag)
          temp->rc=save->lc;
     else
           temp->lc=save->rc;
     tree->value=save->value;
     return tree;
}
 
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The function name is "what" so I suspect this is a textbook or homework or exam problem. :smile:

Have you tried drawing a diagram of an example tree, with arrows for pointers, and rearranging the arrows according to the statements? A visual representation of what's happening might make things more clear.
 
what kind of tree should i try ??
how big
what values
?
 
what commands in this code are changing the structure of the tree?
lines like this:
Code: 
save=save->lc;
only changes our perspective on the tree
this line only makes us look on a different section of a tree
 
transgalactic said:
what kind of tree should i try ??
how big
what values
?

Code: 
typedef struct node node;         //node is alias for struct node
struct node{                               
    int value,count;
    node *lc,*rc;
};
I would say a binary tree.

Try some different examples. An empty tree, one with no left node, one with no right node, one with both, etc. See what result you get.