#include <iostream>
#include <string>
#include <cstdlib>
using namespace std;

//number guessing program.
//computer generates a random number
//user guesses a number
//computer responds with "high, low, or correct"
//continue until user has guessed the number

int main(){

    int turn = 0;
    int guess = 50;
	int diff = 25;
	bool correct = 0;
	string input = "";
	
	cout << "pick a number from 1 to 100" << endl;
	cout << "the computer will attempt to guess your number" << endl;
	cout << "enter \"low\", \"high\" or \"correct\"" << endl;
	
    while(!correct){
    
        turn++; // start with turn 1
        cout << turn << ": " << guess << endl; // present user with guess
        
        getline(cin, input); // high, low, or correct
        
        if (!input.compare("low")){ // user entered "low"
            guess = guess + diff; // guess higher
        } else if (!input.compare("high")){ // user entered "high"
            guess = guess - diff; // guess lower
    	} else if(!input.compare("correct")) { // user entered "correct"
    		correct = 1;  // exit the loop
        } else { // invalid response
        	cout << "please enter a valid response" << endl;
        	turn--; // turn does not count
        }// end if

        diff = (diff / 2) + (diff % 2); // diff cannot be zero

    } // end while
    cout << guess << " is correct!" << endl;
    cout << "It took " << turn << " turns." << endl;
    return EXIT_SUCCESS;
} // end main