Evaluate a boolean expression represented as string
Given a string consisting of only 0, 1, A, B, C where
A = AND
B = OR
C = XOR
Calculate the value of the string assuming no order of precedence and evaluation is done from left to right.
Constraints – The length of string will be odd. It will always be a valid string.
Example, 1AA0 will not be given as an input.
Examples:
Input : 1A0B1 Output : 1 1 AND 0 OR 1 = 1 Input : 1C1B1B0A0 Output : 0
Source : Microsoft online round for internship 2017
The idea is to traverse all operands by jumping a character after every iteration. For current operand str[i], check values of str[i+1] and str[i+2], accordingly decide the value of current subexpression.
C++
// C++ program to evaluate value of an expression. #include <bits/stdc++.h> using namespace std; int evaluateBoolExpr(string s) { int n = s.length(); // Traverse all operands by jumping // a character after every iteration. for (int i = 0; i < n; i += 2) { // If operator next to current operand // is AND. if (s[i + 1] == 'A') { if (s[i + 2] == '0'|| s[i] == '0') s[i + 2] = '0'; else s[i + 2] = '1'; } // If operator next to current operand // is OR. else if (s[i + 1] == 'B') { if (s[i + 2] == '1'|| s[i] == '1') s[i + 2] = '1'; else s[i + 2] = '0'; } // If operator next to current operand // is XOR (Assuming a valid input) else { if (s[i + 2] == s[i]) s[i + 2] = '0'; else s[i + 2] = '1'; } } return s[n - 1] -'0'; } // Driver code int main() { string s = "1C1B1B0A0"; cout << evaluateBoolExpr(s); return 0; } |
Java
// Java program to evaluate value of an expression. public class Evaluate_BoolExp { // Evaluates boolean expression // and returns the result static int evaluateBoolExpr(StringBuffer s) { int n = s.length(); // Traverse all operands by jumping // a character after every iteration. for (int i = 0; i < n; i += 2) { // If operator next to current operand // is AND. if( i + 1 < n && i + 2 < n) { if (s.charAt(i + 1) == 'A') { if (s.charAt(i + 2) == '0' || s.charAt(i) == 0) s.setCharAt(i + 2, '0'); else s.setCharAt(i + 2, '1'); } // If operator next to current operand // is OR. else if ((i + 1) < n && s.charAt(i + 1 ) == 'B') { if (s.charAt(i + 2) == '1' || s.charAt(i) == '1') s.setCharAt(i + 2, '1'); else s.setCharAt(i + 2, '0'); } // If operator next to current operand // is XOR (Assuming a valid input) else { if (s.charAt(i + 2) == s.charAt(i)) s.setCharAt(i + 2, '0'); else s.setCharAt(i + 2 ,'1'); } } } return s.charAt(n - 1) - '0'; } // Driver code public static void main(String[] args) { String s = "1C1B1B0A0"; StringBuffer sb = new StringBuffer(s); System.out.println(evaluateBoolExpr(sb)); } } // This code is contributed by Sumit Ghosh |
Python3
# Python3 program to evaluate value # of an expression. import math as mt def evaluateBoolExpr(s): n = len(s) # Traverse all operands by jumping # a character after every iteration. for i in range(0, n - 2, 2): # If operator next to current # operand is AND.''' if (s[i + 1] == "A"): if (s[i + 2] == "0" or s[i] == "0"): s[i + 2] = "0" else: s[i + 2] = "1" # If operator next to current # operand is OR. elif (s[i + 1] == "B"): if (s[i + 2] == "1" or s[i] == "1"): s[i + 2] = "1" else: s[i + 2] = "0" # If operator next to current operand # is XOR (Assuming a valid input) else: if (s[i + 2] == s[i]): s[i + 2] = "0" else: s[i + 2] = "1" return ord(s[n - 1]) - ord("0") # Driver code s = "1C1B1B0A0"string=[s[i] for i in range(len(s))] print(evaluateBoolExpr(string)) # This code is contributed # by mohit kumar 29 |
C#
// C# program to evaluate value // of an expression. using System; using System.Text; class GFG { // Evaluates boolean expression // and returns the result public static int evaluateBoolExpr(StringBuilder s) { int n = s.Length; // Traverse all operands by jumping // a character after every iteration. for (int i = 0; i < n; i += 2) { // If operator next to current // operand is AND. if (i + 1 < n && i + 2 < n) { if (s[i + 1] == 'A') { if (s[i + 2] == '0' || s[i] == 0) { s[i + 2] = '0'; } else { s[i + 2] = '1'; } } // If operator next to current // operand is OR. else if ((i + 1) < n && s[i + 1] == 'B') { if (s[i + 2] == '1' || s[i] == '1') { s[i + 2] = '1'; } else { s[i + 2] = '0'; } } // If operator next to current operand // is XOR (Assuming a valid input) else { if (s[i + 2] == s[i]) { s[i + 2] = '0'; } else { s[i + 2] = '1'; } } } } return s[n - 1] - '0'; } // Driver code public static void Main(string[] args) { string s = "1C1B1B0A0"; StringBuilder sb = new StringBuilder(s); Console.WriteLine(evaluateBoolExpr(sb)); } } // This code is contributed by Shrikant13 |
PHP
<?php // PHP program to evaluate value // of an expression. function evaluateBoolExpr($s) { $n = strlen($s); // Traverse all operands by jumping // a character after every iteration. for ($i = 0; $i < $n; $i += 2) { // If operator next to current operand // is AND. if (($i + 1) < $n && $s[$i + 1] == 'A') { if ($s[$i + 2] == '0'|| $s[$i] == '0') $s[$i + 2] = '0'; else $s[$i + 2] = '1'; } // If operator next to current operand // is OR. else if (($i + 1) < $n && $s[$i + 1] == 'B') { if ($s[$i + 2] == '1'|| $s[$i] == '1') $s[$i + 2] = '1'; else $s[$i + 2] = '0'; } // If operator next to current operand // is XOR (Assuming a valid input) else { if (($i + 2) < $n && $s[$i + 2] == $s[$i]) $s[$i + 2] = '0'; else $s[$i + 2] = '1'; } } return $s[$n - 1] -'0'; } // Driver code $s = "1C1B1B0A0"; echo evaluateBoolExpr($s); // This code is contributed // by Akanksha Rai |
Output:
0
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