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Evaluate a boolean expression represented as string in C++
In this problem, we are given a string exp that represents a boolean expression. Our task is to evaluate the boolean expression represented as String.
The valid characters in the expression are −
0 or 1 denoting the boolean value
& denoting AND operation
| denoting OR operation
^ denoting XOR operation
We need to solve this expression and return the result.
Let's take an example to understand the problem,
Input: str = 1&1|0^1^0&1
Output: 0
Explanation:
1&1|0^1^0&1
1 AND 1 OR 0 XOR 1 XOR 0 AND 1
1 OR 0 XOR 1 XOR 0 AND 1
1 XOR 1 XOR 0 AND 1
0 XOR 0 AND 1
0 AND 1
0
Solution Approach:
A simple solution is to check the current values and then perform operations one by one. For this we will consider 3-3 characters of the string and then return their result.
Program to illustrate the working of our solution,
Example
#include <iostream>
using namespace std;
int andOperation(int a, int b){
return a & b;
}
int orOperation(int a, int b){
return a | b;
}
int xorOperation(int a, int b){
return a^b;
}
char solveExpression(string s) {
int n = s.length();
for (int i = 0; i < n; i += 2) {
if (s[i + 1] == '&') {
s[i + 2] = andOperation(s[i], s[i + 2]);
}
else if (s[i + 1] == '+') {
s[i + 2] = orOperation(s[i], s[i + 2]);
}
else {
s[i + 2] = xorOperation(s[i], s[i + 2]);
}
}
return s[n - 1] ;
}
int main() {
string expr = "0^1+0+1&1";
cout<<"The result of expression "<<expr<<" is "<<solveExpression(expr);
return 0;
}Output −
The result of expression 0^1+0+1&1 is 1
Updated on: 22-Jan-2021
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