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JavaScript JavaScript Loops, Arrays and Objects Simplify Repetitive Tasks with Loops A Closer Look at Loop Conditions

Joshua Thomas
Joshua Thomas
2,807 Points
Posted by Joshua Thomas
Joshua Thomas
2,807 Points

Code for the computer to guess in less tries

While not exactly a question I figured I'd share the code to people who are interested. Anyways basically what it does, when the computer guess the number, it will be told if the number is higher or lower than what it guessed. From that the computer will change the range of values accordingly, and guess again. This will repeat until it guesses correctly.

var lower = 1;
var upper = 10000;
var randomNumber = getRandomNumber(lower, upper);
var guess;lower
var attempts = 0;

function getRandomNumber(lower, upper) {
  return Math.floor( Math.random() * (upper - lower + 1)) + lower;
}

while ( guess !== randomNumber ) {
  guess = getRandomNumber(lower, upper ); 
  attempts++;
    if (guess > randomNumber) {
      upper = guess; }
    else if (guess < randomNumber) {
      lower = guess; 
    }

}

document.write("<p> The random number was: " + randomNumber + "<p>");
document.write("<p> It took the computer " + attempts + " attempts to get it right.</p>")

If you have any questions about the code here. Feel free to ask :) This allows it to guess a number from 1 - 10000 in about 20 tries.

Jason Anello
Jason Anello
Courses Plus Student 94,610 Points

fixed code formatting

3 Answers

Umesh Ravji
Umesh Ravji
42,386 Points
Umesh Ravji
Umesh Ravji
42,386 Points

Hi Joshua, that's a good way to approach the problem, but see what happens when you just pick the number that is half-way between your lower and upper each time.

var lower = 1;
var upper = 10000;
var randomNumber = getRandomNumber(lower, upper);
var guess;
var lower; 
var attempts = 0;

function getRandomNumber(lower, upper) {
  return Math.floor( Math.random() * (upper - lower + 1)) + lower;
}

function getHalf(lower, upper) {
  return Math.floor((lower + upper) / 2);
}

while ( guess !== randomNumber ) { 
  guess = getHalf(lower, upper);
  attempts++;
  if (guess > randomNumber) {
    upper = guess;
  } else if (guess < randomNumber) { 
    lower = guess; 
  }
}

document.write("<p> The random number was: " + randomNumber + "<p>");
document.write("<p> It took the computer " + attempts + " attempts to get it right.</p>");
Dennis Amiel Domingo
Dennis Amiel Domingo
15,357 Points

I think for Umesh Ravji's version, the computer will have a smaller chance to answer the random number at the very first try (because computer's try#1 will always be equal to 5000) . But that's just what I think, and I'm a noob lol.

Dennis Amiel Domingo
Dennis Amiel Domingo
15,357 Points
Dennis Amiel Domingo
Dennis Amiel Domingo
15,357 Points

I just don't understand what the "++" in attempts is. Or maybe I haven't gotten to that part yet.

Umesh Ravji
Umesh Ravji
42,386 Points
Umesh Ravji
Umesh Ravji
42,386 Points

Hi Dennis, attempts++ is just shorthand for attempts = attempts + 1

Tt can also be written as attempts += 1.

Dennis Amiel Domingo
Dennis Amiel Domingo
15,357 Points
Dennis Amiel Domingo
Dennis Amiel Domingo
15,357 Points

Thanks Umesh!