Beginner excersise problem

[IronmanCro]

Hi all, i started to practice true those excersises that i found on this forum. I camed to Bracketing Search, and i did manage to solve first two modifications, but i just can't figure out how to make a computer guess the number in 7 attempts. My head is gonna burst lol, for two days i've been trying to figure it out, writing on paper, trying empiricly, nothing. My code will find the number for sure, but not in maximum of 7 attempts in any scenario.

Any help and guidance is very much appriciated. Btw i also feel my code is complete rubish, seams as too many code lines for the task, any suggestion?


Bracketing Search
Requires:
variables, data types, and numerical operators
basic input/output
logic (if statements, switch statements)
loops (for, while, do-while)
psudo random numbers

Write a program that calculates a random number 1 through 100. The program then asks the user to guess the number.
If the user guesses too high or too low then the program should output "too high" or "too low" accordingly.
The program must let the user continue to guess until the user correctly guesses the number.

★ Modify the program to output how many guesses it took the user to correctly guess the right number.

★★ Modify the program so that instead of the user guessing a number the computer came up with, the computer guesses the number that the user has secretely decided. The user must tell the computer whether it guesed too high or too low.

★★★★ Modify the program so that no matter what number the user thinks of (1-100) the computer can guess it in 7 or less guesses.

my code

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

int main() {

	int mode, times = 1;// sets mode for switch case
	int userNumber; //takes user input
	int divider; //divider
	string directions; //
	srand(time(0));
	int computerNumber = 1+(rand()%100); // generates random number between 1-100


	cout << "Enter a number between 1-100 for computer to try and guess it\nNumber: ";
	cin >> userNumber;

	if(computerNumber<userNumber){
		mode = 0;//if computer number is smaller than user number do case 0
	}

	else if (computerNumber>userNumber){
		mode = 1;//if computer number is bigger than user number do case 1
	}

	divider = computerNumber;

	switch(mode){

		case 0:
			while(computerNumber != userNumber){

				times++;
				cout << computerNumber;
				cout << ":";
				cin >> directions;

				if(directions == "L"){  // too low
					computerNumber += divider;
					if (computerNumber > 100) goto here;

				}else if(directions == "H"){ // too high
					here:
					here2:
					if(divider != 1){ //limits divider variable to hold minimum of 1
					divider /= 2;
					}
					computerNumber -= divider;
					if(computerNumber > 100) goto here2;//prevents computer from displaying number greater than 100 because 1-100
				}
			}
			break;



		case 1:
			while(computerNumber != userNumber){

				times++;
				cout << computerNumber;
				cout << ":";
				cin >> directions;

				if(directions == "L"){ // too low

					divider /= 2;
					computerNumber += divider;

				}else if(directions == "H"){  //Too high

					if(divider != 1){ //limits divider variable to hold minimum of 1
					divider /= 2;
					}
					computerNumber -= divider;

					if(computerNumber == 0){//prevents computer from "saying" 0 because the task was to find a number between 1-100
						computerNumber++;
					}
				}

			}
			break;


	}


	cout << computerNumber << ": Win!" << endl << endl;
	cout << "Computer found the number, the number was " << computerNumber << "!" << endl;
	cout << "It took " << times << " attempts for computer to guess it!" << endl;
}

Enter a number between 1-100 for computer to try and guess it
Number: 1
54:H
27:H
14:H
8:H
5:H
4:H
3:H
2:H
1: Win!

Computer found the number!
It took computer 9 attempts to guess the right number!

[toum]

The problem comes from the way you're computing your step size from it's previous value.
Each time your step size is odd, dividing it by 2 makes it smaller than what it should be.

As you can see in your example, its value falls down to 1 much too soon.
To correct that, change divider /= 2; with divider = (divider+1)/2;.

By the way, when using this method, the starting value for the computer guess should not be random. It should be the middle value of the expected range of input, ie 50.

[IronmanCro]

But doesn't it say computer has to make a random number in excersise description? Or maybe i misunderstood it, english is not my native language so theres that.

Btw thx for helping me out, much appriciated :)

[toum]

English is not my native language either.

From what I understand, it's only for the first question that the computer has to pick a random value.

[IronmanCro]

Oh, i see, yeah that makes sense then, it is possible to find it in 7 attempts then. Much abliged :)