Guessing Game / Bracketing Search

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


int tooHigh(int& n);
int tooLow(int& n);
int computerGuess(string highOrLow, int& max, int& min, int guess);
int checkGuess(int guess, int randm, int& tries);
int randomNum();






int main()
{
    int guess = 50;
    int tries = 0;
    int selection = 99;
    int randm = 0;


    cout<<"\t\t\tWELCOME TO THE GUESSING GAME!\n\n"<<endl;


    do
    {
        cout<<"\n\t 1. Human Vs. Computer - human Guesses."<<endl;
        cout<<"\n\t 2. Computer Vs. Human - Computer Guesses."<<endl;

        cout<<"\nPlease choose one of the play types (0 to exit): ";
        cin>>selection;


        switch(selection)
        {
            case 1:



                randm = randomNum();
                cout<<"\nThe computer has guessed a number between 0 and 100."<<endl;
                cout<<"Please enter your guess: ";

                do
                {
                    cin>>guess;
                    cin.ignore();

                    checkGuess(guess, randm, tries);

                }while(guess != randm);

                cout<<"Thank you! You got it in "<<tries<<" tries."<<endl;
                tries = 0;

                cin.ignore();
                break;

            case 2:

                string highOrLow = "ERROR"; //user will enter wether computer guessed too high or too low

                int max = 101;
                int min = 0;

                cout<<"\nPlease Think of a number between 0 - 100"<<endl;
                cout<<"The computer will attempt to guess your number."<<endl;
                cout<<"Type in \"high\" if the number printed is too high."<<endl;
                cout<<"Type in \"low\" if the number printed is too low."<<endl;
                cout<<"Type in \"done\" if the number printed is what you guessed."<<endl;

                do
                {
                    guess = computerGuess(highOrLow, max, min, guess);
                    cout<<"\nGuess number "<<tries+1<<" is "<< guess<<endl;
                    //cout<<"Max: "<<max<<endl;
                    //cout<<"Min :"<<min<<endl;
                    cin>>highOrLow;
                    tries++;

                }while(highOrLow != "done");

                cout<<"Glad thats over!"<<endl;
                tries = 0;

                break;

        }

    }while(selection != 0);
}

int computerGuess(string highOrLow, int& max, int& min, int guess)
{
    if(highOrLow == "high")
    {
        max = guess;
        guess = (min+max)/2;

        return guess;
    }

    else if(highOrLow == "low")
    {
        min = guess;
        guess = (min+max)/2;

        return guess;
    }

    else
    {
        guess = (min+max)/2;

        return guess;
    }
}

int checkGuess(int guess, int randm, int& tries)
{
    if(guess < randm)
    {
        cout<<"Too Low!"<<endl;
    }

    else if(guess > randm)
    {
        cout<<"Too High!"<<endl;
    }

    else
    {
        cout<<"Perfect!"<<endl;
    }

    return tries++;
}

int randomNum()
{
    srand(time(NULL));
    int randm = (rand() % 100) + 1;

    return randm;
}