Thread: want to return a node using recursion

So the task is to find the node with minimum value of a binary tree (not binary search tree). the input is the pointer to the root of the tree. and i cannot make recursion work when i do if conditions. here is what i have

Code:

​/*function 3-takses as input the pointer to the root of the tree and returns a pointer to the node with the minimum value*/
CPPtr minimumvalue(CPPtr SP){    


    CPPtr min = NULL;    //node of minimum value


        if(SP== NULL){    // if there is a node, begin comparing
            return NULL;
        }
        else{
            if(SP->data<SP->left->data){    //if the node has smaller value than its left child
                min = SP;                    //update node of minimum value
            }
            else min = SP->left;                //if the node has greater value than its left child 
                                                //update node to the child


            if (min->data > SP->right->data){ //if the updated node has smaller value than right child
                min = SP->right;                    //update node
            }
            


                CPPtr minl = minimumvalue(SP->left);                //check for left subtree
            //    CPPtr minr = minimumvalue(SP->right);                //check for right subtree
        
            return min;
        }
}

no matter where i call my function i get errors like unhandled exception at some memory.
anyone have idea on how to use recursion in this?

Originally Posted by stahta01

Before checking the value of "SP->left->data" You should check to make sure SP->left" is NOT NULL.
The same for the right side.

Tim S.

hi Tim, it seems there is a problem with my 1st if condition. now the code is giving NULL regardless.

Code:

CPPtr minimumvalue(CPPtr SP){	

	CPPtr min = NULL;	//node of minimum value


		if(SP== NULL){	// if there is a node, begin comparing
			return NULL;
		}
		else{
			if(SP->left!=NULL && SP->data<SP->left->data){	//if the node has smaller value than its left child
				min = SP;					//update node of minimum value
			}
			else min = SP->left;				//if the node has greater value than its left child 
												//update node to the child


			if (SP->right!=NULL && min->data > SP->right->data){ //if the updated node has smaller value than right child
				min = SP->right;					//update node
			}
			


				 min = minimumvalue(SP->left);				//check for left subtree
				 min = minimumvalue(SP->right);				//check for right subtree
		
			return min;
		}
}

Originally Posted by phantomotap

O_o

Yog Sothoth!

Please, for all that is good and decent in the world, don't `typedef' pointers. (*)

You may see it as easier now, but imagine trying to work with several others each of whom has a different preference for how to style the names of such `typedef' pointers.

Actually, let me just tell you: it is awful. Please don't be a part of the problem.

*shrug*

In any event, if the tree isn't a tree specifically organized nodes you must always visit every node (to consider every nodes value). You appear to be... never doing that.

[Edit]
This is simply extra; Tim is addressing your issue.
[/Edit]

Soma

(*) Or bad and kinky if your that sort. (Call me!)

thanks for the advice! i will remember this when i code next time as this was my teachers idea to typedef

Originally Posted by stahta01

Instead of



Do


This means you always assign a value to min; your if logic did NOT always do this.

Edit: Your code still has more logic bugs; but, you need to find then and fix them.

Tim S.

thanks!