CodeCombat: Binary Search Solution

coco.binary.search.js

// http://codecombat.com/play/level/binary-search

// Guess the number that the paladin is thinking of each round.
// She will indicate whether the answer is a higher or lower number after each guess.
// She moves to x<39.5 if lower and x>40.5 if higher 
// and x==40 if correct.
// The paladin's maxNum property is the upper bound of the number.

var paladin = this.findNearest(this.findFriends());

while(true) {
    var minGuess = 0;               // minimum possible number
    var maxGuess = paladin.maxNum;  // maximum possible number
    var midGuess;                   // your guess
    
    minGuess = minGuess - 1;        // include 0 in guess range
    
    while(minGuess <= maxGuess) {
        midGuess = Math.ceil( minGuess + ((maxGuess - minGuess) / 2) );
        this.say(midGuess);
        
        // If paladin moves left, guess lower
        if (paladin.pos.x < 39.5) {
            maxGuess = midGuess;
        }
        
        // If paladin moves right, guess higher
        else if (paladin.pos.x > 40.5) {
            minGuess = midGuess;
        }
        
        // We guessed correctly
        else {
            break;
        }
    }
}