Check if all leaves are at same level | GeeksforGeeks

Check if all leaves are at same level | GeeksforGeeks

Given a Binary Tree, check if all leaves are at same level or not.

Given Inorder and Preorder traversals of a binary tree, print Postorder traversal.

The idea is, root is always the first item in preorder traversal and it must be the last item in postorder traversal. We first recursively print left subtree, then recursively print right subtree. Finally, print root. To find boundaries of left and right subtrees in pre[] and in[], we search root in in[], all elements before root in in[] are elements of left subtree and all elements after root are elements of right subtree. In pre[], all elements after index of root in in[] are elements of right subtree. And elements before index (including the element at index and excluding the first element) are elements of left subtree.

The length of left or right tree is same in both in-order or preorder.

// Prints postorder traversal from given inorder and preorder traversals

void printPostOrder(int in[], int pre[], int n)

{

   // The first element in pre[] is always root, search it

   // in in[] to find left and right subtrees

   int root = search(in, pre[0], n);

   // If left subtree is not empty, print left subtree

   if (root != 0)

      printPostOrder(in, pre+1, root);

   // If right subtree is not empty, print right subtree

   if (root != n-1)

      printPostOrder(in+root+1, pre+root+1, n-root-1);

   // Print root

   cout << pre[0] << " ";

}

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