Construct_Binary_Tree_from_Inorder_and_Postorder.cpp

struct Node
{
    int data;
    struct Node* left;
    struct Node* right;

    Node(int x){
        data = x;
        left = right = NULL;
    }
};*/

class Solution
{
    public:

    //Function to return a tree created from postorder and inoreder traversals.
    Node *buildTree(int in[], int post[], int n) {
        if (n == 0) {
            return nullptr;
        }
        int rootIndex = 0;
        while (rootIndex < n && in[rootIndex] != post[n - 1]) {
            rootIndex++;
        }
        Node* root = new Node(post[n - 1]);
        Node* leftSubtree = buildTree(in, post, rootIndex);
        Node* rightSubtree = buildTree(in + rootIndex + 1, post + rootIndex, n - rootIndex - 1);
        root->left = leftSubtree;
        root->right = rightSubtree;
        return root;
    }
};