Flatten Binary Tree to Linked List doubt

#1

When i’m doing a dry run I’m getting the right result but I can’t understand why its showing a runtime error on leetcode.

Here’s my code-

#2

Hey @nidhigupta847

if(prev==NULL)
{ head=root;
}
else
{
root->left=prev;(LINE1)
prev->right=root;
}
prev=root;
preo(root->left);(Line 2)
preo(root->right);

ur code is not even working for
…1
.2 null

In line 1 u are making left of root as prev and in line 2 making recursive call to root->left which makes it go in infinite loop.

Here follow this for correct implementation

` void flatten(struct Node* root)
{
// base condition- return if root is NULL
// or if it is a leaf node
if (root == NULL || root->left == NULL &&
root->right == NULL) {
return;
}

// if root->left exists then we have 
// to make it root->right
if (root->left != NULL) {

    // move left recursively
    flatten(root->left);

    // store the node root->right
    struct Node* tmpRight = root->right;
    root->right = root->left;
    root->left = NULL;

    // find the position to insert
    // the stored value   
    struct Node* t = root->right;
    while (t->right != NULL) {
        t = t->right;
    }

    // insert the stored value
    t->right = tmpRight;
}

// now call the same function
// for root->right
flatten(root->right);

}`

#3

I hope I’ve cleared your doubt. I ask you to please rate your experience here
Your feedback is very important. It helps us improve our platform and hence provide you
the learning experience you deserve.

On the off chance, you still have some questions or not find the answers satisfactory, you may reopen
the doubt.