Chapter 6 - Question 15
Program the computer to ask a user to, "think of a three-digit number". Using the response "Y"and "N" to the question, "Is your number bigger than n" (where n is computed by the program), find the user's three-digit number.
Solution 1
PHP isn't a logical language to use when asking for user input multiple times, so I've written this solution in c++.
// this handles input and output#include <iostream.h>int main (){ // the guess is the amount the user will be asked // the code can handle any min/max values if they're valid int iGuess, iMin = 111, iMax = 999; // the users response should be 1 if true and 0 if false int iResponse; // tell the user to think of a three digit number cout << "Think of a three digit number.\n" << "...\n"; // only loop while the min and max values are different // which means we are still guessing while (iMin!=iMax) { // guess half way between the min and max values // this will find the answer in the smallest number of questions iGuess = (iMin+iMax)/2; // ask the user cout << "Is your number bigger than " << iGuess << "?\n>"; // get their response cin >> iResponse; // if they answered that the number is bigger if (iResponse == 1) // we know the minimum is the amount plus one iMin = iGuess+1; else // it must be lower, so set the max to the guess iMax = iGuess; // when the min and max are the same, their can only be one answer if (iMin == iMax) // let the user know we found their number cout << "You were thinking of " << iMin << "!"; } return 0;}Which produces:
Log
- March 29, 2005 - Added solution 1.