Evaluation of Expression Tree

Source: Internet
Author: User

Evaluation of Expression Tree

Given A simple expression tree, consisting of basic binary operators i.e., +, –,* and/and some integers, evaluate the Expression tree.


Input:root node of the below Treeoutput:100input:root node of the below treeoutput:110

We strongly recommend minimize your browser and try this yourself first.

As all of the operators in the tree is binary hence each node would have either 0 or 2 children. As it can be inferred from the examples above, the integer values would appear at the leaf nodes, while the interior nod ES represent the operators.
To evaluate the syntax tree, a recursive approach can be followed.

Algorithm:let t be the syntax Treeif  t was not null then      If t.info are operand then           Return  t.info      else< C6/>a = Solve (t.left)         B = Solve (t.right)         return A operator B         where operator is the info contained in T

The time complexity would was O (n), as each node is visited once. Below is a C + + program for the same:

1#include <iostream>2#include <cstdlib>3 using namespacestd;4 5typedefstructnode{6     strings;7Node *Left ;8Node *Right ;9Nodestringx): S (x), left (null), right (null) {}Ten }node; One  A //Utility function to return the integer value - //of a given string - intToInt (strings) { the     intLen =s.length (); -     intnum =0; -      for(inti =0; i < Len; i++){ -num = num *Ten+ (s[i]-'0'); +     } -     returnnum; + } A  at //Check which operator to apply - intCalculateConst Char*c,intLval,intrval) { -     intans; -     Switch(*c) { -      Case '+': ans = lval + rval; Break; -      Case '-': ans = lval-rval; Break; in      Case '*': ans = lval * rval; Break; -      Case '/': ans = lval/rval; Break; to     } +     returnans; - } the  * //This function receives a node of the syntax tree $ //and recursively evaluates itPanax Notoginseng intEval (Node *root) { -     //Empty Tree the     if(Root = =NULL) +         return 0; A     //leaf node i.e, an integer the     if(Root->left = = NULL && Root->right = =NULL) +         returnToInt (root->s); -     //Evaluate left subtree $     intLval = eval (root->Left ); $     //Evaluate Right subtree -     intRval = eval (root->Right ); -     returnCalculate ((root->s). C_str (), lval, rval); the } - Wuyi intMain () the { -     //Create a syntax tree WuNode *root =NewNode"+"); -Root->left =NewNode"*"); AboutRoot->left->left =NewNode"5"); $Root->left->right =NewNode"4"); -Root->right =NewNode"-"); -Root->right->left =NewNode" -"); -Root->right->right =NewNode" -"); Acout << eval (root) <<Endl; +   the     Delete(root); -   $Root =NewNode"+"); theRoot->left =NewNode"*"); theRoot->left->left =NewNode"5"); theRoot->left->right =NewNode"4"); theRoot->right =NewNode"-"); -Root->right->left =NewNode" -"); inRoot->right->right =NewNode"/"); theRoot->right->right->left =NewNode" -"); theRoot->right->right->right =NewNode"2"); About   thecout <<eval (root); theSystem"Pause"); the     return 0; +}



Reference: http://www.geeksforgeeks.org/evaluation-of-expression-tree/

Evaluation of Expression Tree

Contact Us

The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion; products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the content of the page makes you feel confusing, please write us an email, we will handle the problem within 5 days after receiving your email.

If you find any instances of plagiarism from the community, please send an email to: info-contact@alibabacloud.com and provide relevant evidence. A staff member will contact you within 5 working days.

A Free Trial That Lets You Build Big!

Start building with 50+ products and up to 12 months usage for Elastic Compute Service

  • Sales Support

    1 on 1 presale consultation

  • After-Sales Support

    24/7 Technical Support 6 Free Tickets per Quarter Faster Response

  • Alibaba Cloud offers highly flexible support services tailored to meet your exact needs.