`{"id":"b7a7d625-3e13-4667-82c1-3d7e10baa565","name":"Construct Binary Tree From Preorder And Postorder Traversal","description":"1. You are given a partially written function to solve(Refer question video).\r\n2. you will be given two arrays representing a valid PostOrder & PostOrder of a Binary Tree. Program is required to create a unique Binary Tree.\r\n","inputFormat":"Input is managed for you.","outputFormat":"Input is managed for you.","constraints":"0 &lt;= Number of Nodes &lt;= 10^9\r\n-10^9 &lt;= value of Node data &lt;= 10^9\r\nValid PreOrder and PostOrder traversals.","sampleCode":{"cpp":{"code":"#include <iostream>\r\n#include <vector>\r\nusing namespace std;\r\n\r\nclass TreeNode\r\n{\r\npublic:\r\n int val = 0;\r\n TreeNode *left = nullptr;\r\n TreeNode *right = nullptr;\r\n\r\n TreeNode(int val)\r\n {\r\n this->val = val;\r\n }\r\n};\r\n\r\nTreeNode *constructFromPrePost(vector<int> &pre, vector<int> &post)\r\n{\r\n return nullptr;\r\n}\r\n\r\n// input_Section_====================================================================\r\n\r\nvoid display(TreeNode *node)\r\n{\r\n if (node == nullptr)\r\n return;\r\n\r\n string str = \"\";\r\n str += ((node->left != nullptr ? to_string(node->left->val) : \".\"));\r\n str += (\" -> \" + to_string(node->val) + \" <- \");\r\n str += ((node->right != nullptr ? to_string(node->right->val) : \".\"));\r\n\r\n cout << str << endl;\r\n\r\n display(node->left);\r\n display(node->right);\r\n}\r\n\r\nvoid solve()\r\n{\r\n int n;\r\n cin >> n;\r\n vector<int> post(n, 0);\r\n for (int i = 0; i < n; i++)\r\n {\r\n cin >> post[i];\r\n }\r\n\r\n vector<int> pre(n, 0);\r\n for (int i = 0; i < n; i++)\r\n {\r\n cin >> pre[i];\r\n }\r\n\r\n TreeNode *root = constructFromPrePost(pre, post);\r\n display(root);\r\n}\r\n\r\nint main()\r\n{\r\n solve();\r\n return 0;\r\n}"},"java":{"code":"import java.util.Scanner;\r\n\r\npublic class Main {\r\n public static Scanner scn = new Scanner(System.in);\r\n\r\n public static class TreeNode {\r\n int val = 0;\r\n TreeNode left = null;\r\n TreeNode right = null;\r\n\r\n TreeNode(int val) {\r\n this.val = val;\r\n }\r\n }\r\n\r\n public static TreeNode constructFromPrePost(int[] pre, int[] post) {\r\n return null;\r\n }\r\n\r\n // input_section=================================================\r\n\r\n public static void display(TreeNode node) {\r\n if (node == null)\r\n return;\r\n\r\n StringBuilder sb = new StringBuilder();\r\n sb.append((node.left != null ? node.left.val : \".\"));\r\n sb.append(\" -> \" + node.val + \" <- \");\r\n sb.append((node.right != null ? node.right.val : \".\"));\r\n\r\n System.out.println(sb.toString());\r\n\r\n display(node.left);\r\n display(node.right);\r\n\r\n }\r\n\r\n public static void solve() {\r\n int n = scn.nextInt();\r\n int[] post = new int[n];\r\n for (int i = 0; i < n; i++)\r\n post[i] = scn.nextInt();\r\n\r\n int[] pre = new int[n];\r\n for (int i = 0; i < n; i++)\r\n pre[i] = scn.nextInt();\r\n\r\n TreeNode root = constructFromPrePost(pre, post);\r\n display(root);\r\n }\r\n\r\n public static void main(String[] args) {\r\n solve();\r\n }\r\n}"},"ruby":{"code":""},"python":{"code":""},"javascript":{"code":""}},"points":10,"difficulty":"easy","sampleInput":"7\r\n1 3 2 5 7 6 4\r\n4 2 1 3 6 5 7","sampleOutput":"2 -> 4 <- 6\r\n1 -> 2 <- 3\r\n. -> 1 <- .\r\n. -> 3 <- .\r\n5 -> 6 <- 7\r\n. -> 5 <- .\r\n. -> 7 <- .\r\n","questionVideo":"","hints":[],"associated":[],"solutionSeen":false,"tags":[],"meta":{"path":[{"id":0,"name":"home"},{"id":"0c54b191-7b99-4f2c-acb3-e7f2ec748b2a","name":"Data Structures and Algorithms","slug":"data-structures-and-algorithms","type":0},{"id":"2e9df04c-be14-441c-9a18-8b5a8ca6596d","name":"Trees For Intermediate","slug":"trees-for-intermediate-9994","type":0},{"id":"83c0e437-16cc-4efc-bd84-d32d850bc71a","name":"Construct Binary Tree From Preorder And Postorder Traversal","slug":"construct-binary-tree-from-preorder-and-postorder-traversal","type":1}],"next":{"id":"0962c453-cd78-4bd7-824c-3f0e4b22e828","name":"Construct Binary Tree From Preorder And Postorder Traversal","type":3,"slug":"construct-binary-tree-from-preorder-and-postorder-traversal"},"prev":{"id":"7a50ceec-fc49-4300-8393-27f6abcca35a","name":"Construct binary tree from preorder and inorder traversal","type":3,"slug":"construct-binary-tree-from-preorder-and-inorder-traversal"}}}`

# Construct Binary Tree From Preorder And Postorder Traversal

1. You are given a partially written function to solve(Refer question video). 2. you will be given two arrays representing a valid PostOrder & PostOrder of a Binary Tree. Program is required to create a unique Binary Tree.

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# Construct Binary Tree From Preorder And Postorder Traversal

easy

1. You are given a partially written function to solve(Refer question video). 2. you will be given two arrays representing a valid PostOrder & PostOrder of a Binary Tree. Program is required to create a unique Binary Tree.

## Constraints

0 <= Number of Nodes <= 10^9 -10^9 <= value of Node data <= 10^9 Valid PreOrder and PostOrder traversals.

## Format

### Input

Input is managed for you.

### Output

Input is managed for you.

## Example

Sample Input

```.css-23h8hz{color:inherit;font-size:0.875rem;line-height:1.125rem;letter-spacing:0.016rem;font-weight:var(--chakra-fontWeights-normal);white-space:pre-wrap;}7 1 3 2 5 7 6 4 4 2 1 3 6 5 7```

### Sample Output

`.css-3oaykw{color:var(--chakra-colors-active-primary);font-size:0.875rem;line-height:1.125rem;letter-spacing:0.016rem;font-weight:var(--chakra-fontWeights-normal);white-space:pre-wrap;font-family:Monospace;}2 -> 4 `

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