Construct Tree from Preorder Traversal
Medium Accuracy: 50.68% Submissions: 13461 Points: 4

Construct a binary tree of size N using two given arrays pre[] and preLN[]. Array pre[] represents preorder traversal of a binary tree. Array preLN[] has only two possible values ‘L’ and ‘N’. The value ‘L’ in preLN[] indicates that the corresponding node in Binary Tree is a leaf node and value ‘N’ indicates that the corresponding node is a non-leaf node.
Note: Every node in the binary tree has either 0 or 2 children.

Example 1:

Input :      
N = 5
pre[] = {10, 30, 20, 5, 15}
preLN[] = {N, N, L, L, L}

Output:
          10
        /    \
      30      15
     /  \     
   20    5   

 

Your Task:  
You dont need to read input or print anything. Complete the function constructTree() which takes N, pre[] and preLN[] as input parameters and returns the root node of the constructed binary tree.

Note: The output generated by the compiler will contain the inorder traversal of the created binary tree.
 

Expected Time Complexity: O(N)
Expected Auxiliary Space: O(N)


Constraints:
1 ≤ N ≤ 104
1 ≤ pre[i] ≤ 107
preLN[i]: {'N', 'L'}

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Construct Tree from Preorder Traversal

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