Question

may i ask for help with this c++ problem?

Take your solution (or the posted solution) of Question 2, Assignment 4, and change it to use the new Stack class instead of the STL stack class. Put your main program in RPN.cc. 2. (a) Write a recursive function int find (const int A[I, int n, int x); which returns the first index i = 0, ,n-1 such that A[i] == x, or n if it is not found b)Write a recursive function int rfind(const int ACl, int n, int x); which returns the last index i = 0, , n-1 such that A[i] == x, or n if it is not found (c) Write a program search.cc which asks the user to enter the size of an array, the elements of an array, and an element to search for. For each set of input, the program should print the results of find and rfind. You should allocate the array dynamically. The program should be terminated when 0 is entered for the size of the array.

this is the code i have for assignment 4 question 2:

#include<iostream>

#include<string>

#include<sstream>

#include<stack>

using namespace std;

int main()

{

string inputStr;

stack <int> numberStack;

cout<<"Enter your expression::";

getline(cin,inputStr);

int len=inputStr.length();

stringstream inputStream(inputStr);

string word;

int val,num1,num2;

while (inputStream >> word)

{

//cout << word << endl;

if(word[0] != '+'&& word[0] != '-' && word[0] != '*')

{

val=stoi(word);

numberStack.push(val);

// cout<<"Val:"<<val<<endl;

}

else if(word[0]=='+')

{

num1=numberStack.top();

numberStack.pop();

num2=numberStack.top();

numberStack.pop();

// cout<<num1<<" "<<word<<" "<<num2<<"="<<num1+num2<<endl;

numberStack.push(num1+num2);

}

else if(word[0]=='-')

{

num1=numberStack.top();

numberStack.pop();

num2=numberStack.top();

numberStack.pop();

// cout<<num1<<" "<<word<<" "<<num2<<"="<<num1-num2<<endl;

numberStack.push(num1-num2);

}

else if(word[0]=='*')

{

num1=numberStack.top();

numberStack.pop();

num2=numberStack.top();

numberStack.pop();

// cout<<num1<<" "<<word<<" "<<num2<<"="<<num1*num2<<endl;

numberStack.push(num1*num2);

}

}

int result=numberStack.top();

numberStack.pop();

if(!numberStack.empty())

{

cout<<inputStr<<" is invalid expression."<<endl;

}

else

{

cout<<"Result of RPN::"+inputStr<<" is "<<result<<endl;

}

return 0;

}

Answer 1

#include <iostream>
using namespace std;
//function to find First index of given number
int find(int a[],int n,int num)
{
   int static i=0;
   if(i==n)
   return n;
   if(a[i]==num)
   return i;
   i++;
   return find(a,n,num);
  
}
//function to find last index of given number
int rfind(int a[],int n,int num)
{
   int static i=n-1;
   if(i<0)
   return n;
   if(a[i]==num)
   return i;
   i--;
   return rfind(a,n,num);
}
int main( )
{
   int length;
   cout<<"Enter Array Length:";
   cin>>length;//length of array
   cout<<"\n";
   //cout<<length;
   if(length==0)
   return 0;
   else
   {
   int a[length];//array declaration
   cout<<"Enter elements in an array\n";
   //taking array input from user
   for(int i=0;i<length;i++)
   {
       cin>>a[i];
   }
   cout<<"Enter element to be searched :";
   int search;
   cin>>search;//taking input of search element
   cout<<"\n";
   cout<<"\nFirst Index of search element:(Index starts from zero)";
   cout<<find(a,length,search);//calling find() functin on search element
   cout<<"\n";
   cout<<"\nLast Index of search element:(index starts from zero)";
   cout<<rfind(a,length,search);//calling rfind() function on search element
   }
}