如何更改此代码以仅在找到目标时打印猜测总数

Question

我正在尝试完成对可汗学院的测验。它要求我只在找到目标时打印猜测总数。

测验的链接：link

/* Returns either the index of the location in the array,
  or -1 if the array did not contain the targetValue */
var doSearch = function(array, targetValue) {
    var min = 0;
    var max = array.length - 1;
    var guess;
    while(min <= max) {
        guess = Math.floor((max + min) / 2);
        if (array[guess] === targetValue) {
            return guess;
        else if (array[guess] < targetValue) {
            min = guess + 1;
        }
        else {
            max = guess - 1;
            println(guess);
        }
    }
    return -1;
};


var primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 
              41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97];

var result = doSearch(primes, 73);
println("Found prime at index " + result);

Program.assertEqual(doSearch(primes, 73), 20);

Answer 1

尝试添加一个包含猜测数量的全局变量，并在处理新猜测时递增。在每次新搜索开始时将其设置为零。

到目前为止，您可以将全局变量放入doSearch函数并将doSearch函数返回类型更改为数组。然后，数组可以保存原始返回值和猜测数。

Answer 2

你需要一个变量来记住你的猜测。加

var guesscount;

到你的函数体中定义了其他变量，然后在while循环中通过添加来增加它

guesscount = guesscount + 1;

在你的if语句之前。然后，您可以使用打印结果

println("Number of guesses: " + guesscount);

Answer 3

这是我使用的代码：

    /* Returns either the index of the location in the array,
  or -1 if the array did not contain the targetValue */
var doSearch = function(array, targetValue) {
    var min = 0;
    var max = array.length - 1;
    var guess;
    var guesscount = 0;
    while( min <= max ){
        guess = Math.floor((min + max) / 2);
        println(guess);
        guesscount = guesscount + 1;
        if( array[guess] === targetValue ){
            println("Found prime in " + guesscount + " guesses");
            return guess;
        } else if( array[guess] < targetValue ){
            min = guess + 1;
        } else{
            max = guess - 1;
        }
    }
    return -1;
};

var primes = [2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 
        41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97];

var result = doSearch(primes, 73);
println("Found prime at index " + result);

Program.assertEqual(doSearch(primes, 73), 20);