RecognizedString C++ Algorithm Hi, I need help creating this function. I have a

Question

RecognizedString C++ Algorithm

Hi, I need help creating this function. I have a pseudo-code but I can't get it running in a function, can someone help me?

Here is the pseudo-code:

// Checks the string aString to verify that it is in language L.

// Returns true if aString is in L, false otherwise.

recognizeString(aString: string): boolean

aStack = a new empty stack

// Push the characters that are before the $ (that is, the characters in s) onto the stack

i = 0

ch = character at position i in aString

while (ch is not a '$')

{

aStack.push(ch)

i++

ch = character at position i in aString

}

// Skip the $

i++

// Match the reverse of s

inLanguage = true // Assume string is in language

while (inLanguage and i < length of aString)

{

if (!aStack.isEmpty())

{

stackTop = aStack.peek()

aStack.pop()

ch = character at position i in aString

if (stackTop equals ch)

i++ // Characters match

else

inLanguage = false // Characters do not match (top of stack is not ch )

}

else

inLanguage = false // Stack is empty (first half of string is shorter

// than second half)

}

if (inLanguage and aStack.isEmpty())

aString is in language

else

aString is not in language

Explanation / Answer

#include <iostream>
#include <stack>
using namespace std;

void recognizeString(string str) {

   stack<char> stack;

   int i=0;
   while(str[i] != '$') {
       stack.push(str[i]);
       i++;
   }

   // Skip the $
   i++;

   bool inLanguage = true;
   while (inLanguage && i < str.length()){

       if (!stack.empty()){
           char stackTop = stack.top();
           stack.pop();
           char ch = str[i];
           if (stackTop == ch)
               i++; // Characters match
           else
               inLanguage = false; // Characters do not match (top of stack is not ch )

       }else
           inLanguage = false; // Stack is empty (first half of string is shorter
           // than second half)
   }

   if (inLanguage && stack.empty())
       cout<<"aString is in language"<<endl;
   else
       cout<<"aString is not in language"<<endl;
}

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