Bracketing Search

[Carm]

Hi, I'm doing the exercise on (http://www.cplusplus.com/forum/articles/12974/) called "Bracketing Search", 4 star. I'm pretty close to what I need, but just can't get the computer to always win in under 7 tries.

Tips?

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

int main() {
	int choice = 0;
	int randnum = 0;
	int hotcold = 0;
	int runs = 0;
	int max = 100;
        int min = 1;
	srand((int)time(0));

	do {
		cout << "\nPlease enter a number from 1 to 100 for the computer to guess: ", cin >> choice;
		
		if (choice > 100 || choice < 1)
			cout << "\nNot a number from 1 to 100.\a";
	} while (choice > 100 || choice < 1);

	randnum = rand() % max + 1;

	do {
		cout << "\nComputer chooses " << randnum << ".";
		
		if (randnum == choice) 
			break;
		
		cout << "(1)Lower or (2)Higher? ", cin >> hotcold;

		switch (hotcold) {
		case 1:
			if (max >= randnum)
				max = randnum;
			randnum = rand() % (max - min + 1) + min;
			++runs;
			break;
		case 2:
			if (min <= randnum)
				min = randnum;
			randnum = rand() % (max - min + 1) + min;
			++runs;
			break;
		default:
			cout << "\nNot a choice.\a";
			break;
		}
	} while (runs < 7);

	if ( randnum != choice )
		cout << "\nYou win!";
	else
		cout << "\nComputer wins!";

	cin.ignore(2);
	return 0;
}

[JockX]

Make computer pick the number that is in the middle of available pool of numbers to minimize the number of retries. The rule is to win in 7 or less, so seven is ok.

#include <iostream>	

int main() {
	int results[100];
	for(int goal = 1; goal <= 100; goal++){
		int min = 1;
		int max = 100;
		int last = 50;
		int poolSize = 100;
		std::cout << "Goal: " << goal << " \t";
		int nTries = 1;
		std::cout << "Guessing: ";
		while(true){
			std::cout << last <<", ";
			if(last == goal){
				std::cout << "\n (" << nTries << " tires.)\n";
				break;
			}
			else if(last > goal) {
				max = last;
				poolSize = max - min;
				last = min + floor(poolSize / 2.0); //half rounded down
			}
			else if(last < goal) {
				min = last;
				poolSize = max - min;
				last = min + ceil(poolSize / 2.0); //half rounded up
			}	
			nTries++;
		}
		results[goal-1] = nTries;			
	}
	int timesPerTryCount [10] = {0};
	int mostTries = 0;
	for (int i = 0; i < 100; i++){
		if(mostTries < results[i]){
			mostTries = results[i];
		}
		timesPerTryCount[results[i]]++;
	}
	std::cout << "\nGuessed in\n";
	for(int i = 1; i < 10; i++){
		if(i == 1)
			std::cout << i << " try:\t\t"<< timesPerTryCount[i] << " times\n";
		else
			std::cout << i << " tries:\t"<< timesPerTryCount[i] << " times\n";
	}
	std::cout << "\nMost number of tries: " << mostTries;
	std::cout <<  "\n\nHardest to guess:\n";
	for(int i = 0; i < 100; i++)
	{
		if(results[i] == mostTries)
			std::cout << i+1 << ",\t";
	}
	while(1);
}

[Carm]

I figured that's what I had to do, but I thought that might be cheating haha. I'll try my own approach and see what I can do.

Thanks