Question

Write a function in any functional programming language that will reverse a general list. For example, if an input is (A (B C (D E)) F), output is (F ((E D) C B) A).  Please note that any built-in/pre-defined function, e.g., reverse, cannot be used in your answer.

Please DO NOT hard-code any input values, output values in your code.

Please submit a screenshot of where your code got compiled, executed, showing the execution result

Answer 1

Here we can use stack to reverse the list. I have written very easy logic which could be easily understandable.

#include<bits/stdc++.h>
using namespace std;
int main()
{
  stack<char> stk;
  //taking the complete input first in a string
  string s;
  cout << "Enter the list to be reversed "; //input message
  getline(cin,s);
  for(int i = 0; i<s.length(); i++){
    stk.push(s[i]);  //then pushing each character of the string into stack
  }
  cout << "Output is "; //output message
   //then printing every character one by one
  for(int i = 0; i<s.length(); i++){
    char k = stk.top();
    stk.pop();
    if(k== ')'){ // we have to seperately deal with with the brackets.
      cout << "(";
    }
    else if(k == '('){
      cout << ")";
    }
    else{
      cout << k;
    }
  }
  
}

output will look like below picture. (i have customised the output and input message and it can be removed if required)