add new codes

Author: msdeep14

Diff for: a.out

@@ -0,0 +1,59 @@
+// https://www.geeksforgeeks.org/construct-a-binary-tree-from-postorder-and-inorder/
+#include <bits/stdc++.h>
+using namespace std;
+
+struct Node{
+    int data;
+    Node *left , *right;
+};
+
+Node *getNode(int data){
+    Node *temp = new Node();
+    temp->data = data;
+    temp->left = temp->right = NULL;
+}
+
+int search(int in[], int data, int l, int r){
+    for(int i=l ;i<=r; i++){
+        if(in[i] == data){
+            return i;
+        }
+    }
+    return -1;
+}
+
+Node *buildTree(int in[], int post[], int inStart, int inEnd,int n){
+    static int postIndex = n-1;
+    if(inStart > inEnd)
+        return NULL;
+    Node *root = getNode(post[postIndex]);
+    postIndex -= 1;
+    if(inStart == inEnd)
+        return root;
+
+    int inIndex = search(in,root->data,inStart, inEnd);
+    if(inIndex == -1){
+        cout << "Error\n";
+        return NULL;
+    }
+    
+    root->right = buildTree(in, post, inIndex+1, inEnd,n);
+    root->left = buildTree(in,post,inStart,inIndex-1,n);
+    return root;
+
+}
+
+void inorder(Node *root){
+    if(!root) return;
+    inorder(root->left);
+    cout << root->data << " ";
+    inorder(root->right);
+}
+
+int main(){
+    int post[] = {8,4,5,2,6,7,3,1};
+    int in[] = {4,8,2,5,1,6,3,7};
+    Node *root = buildTree(in,post,0,7,8);
+    inorder(root);
+    return 0;
+}

Diff for: construct-a-binary-tree-from-postorder-and-inorder.cpp

@@ -0,0 +1,58 @@
+// https://www.geeksforgeeks.org/construct-tree-from-given-inorder-and-preorder-traversal/
+#include <bits/stdc++.h>
+using namespace std;
+
+struct Node{
+    char data;
+    Node *left , *right;
+};
+
+Node *getNode(char data){
+    Node *temp = new Node();
+    temp->data = data;
+    temp->left = temp->right = NULL;
+}
+
+int search(int in[], int data, int l, int r){
+    for(int i=l ;i<=r; i++){
+        if(in[i] == data){
+            return i;
+        }
+    }
+    return -1;
+}
+
+Node *buildTree(int in[], int pre[], int inStart, int inEnd){
+    static int preIndex = 0;
+    if(inStart > inEnd)
+        return NULL;
+    Node *root = getNode(pre[preIndex]);
+    preIndex += 1;
+    if(inStart == inEnd)
+        return root;
+
+    int inIndex = search(in,root->data,inStart, inEnd);
+    if(inIndex == -1){
+        cout << "Error\n";
+        return NULL;
+    }
+    root->left = buildTree(in,pre,inStart,inIndex-1);
+    root->right = buildTree(in, pre, inIndex+1, inEnd);
+    return root;
+
+}
+
+void inorder(Node *root){
+    if(!root) return;
+    inorder(root->left);
+    cout << root->data << " ";
+    inorder(root->right);
+}
+
+int main(){
+    int pre[] = {'A','B','D','E','C','F'};
+    int in[] = {'D','B','E','A','F','C'};
+    Node *root = buildTree(in,pre,0,5);
+    inorder(root);
+    return 0;
+}