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.
Implementation:
// 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 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 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.
else if (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# 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 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 |
<script> // Javascript program to evaluate // value of an expression. // Evaluates boolean expression // and returns the result function evaluateBoolExpr(s)
{ let n = s.length;
// Traverse all operands by jumping
// a character after every iteration.
for (let 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].charCodeAt() -
'0' .charCodeAt());
} // Driver code let s = "1C1B1B0A0" ;
let sb = s.split( '' );
document.write(evaluateBoolExpr(sb) + "</br>" );
// This code is contributed by rameshtravel07 </script> |
0
Time Complexity: O(n)
Auxiliary Space: O(n)