Question

此问题的目的是遍历列表，找到列表中的最大值，然后报告最高值的索引值。我能够使用两个for循环来解决这个问题：

var scores = [60, 50, 58, 54, 54, 58, 50, 52, 54, 48, 69, 34, 55, 51, 52, 44, 51, 69, 64, 66, 55, 52, 44, 18, 41, 53, 55, 61, 51, 44];
var highscore = 0;
var highscoreSolutions = [];

for (var i = 0; i < scores.length; i++){
 if (scores[i] > highscore){
     highscore = scores[i];
 } 
}

for (var i = 0; i < scores.length; i++){
 if (scores[i] == highscore){
    highscoreSolutions.push(i);
   }
  }

console.log(highscore);
console.log(highscoreSolutions);

我最初尝试使用一个for循环来解决这个问题，但是我遇到了一个类似的初始化问题，也就是说，无论如何，第一个索引值将包含在最高得分列表中：

var scores = [60, 50, 58, 54, 54, 58, 50, 52, 54, 48, 69, 34, 55, 51, 52, 44, 51, 69, 64, 66, 55, 52, 44, 18, 41, 53, 55, 61, 51, 44];
var highscore = 0;
var highscoreSolutions = [];

for (var i = 0; i < scores.length; i++){
  if (scores[i] >= highscore){
    highscore = scores[i];
    highscoreSolutions.push(i);
  } 
}

console.log(highscore);
console.log(highscoreSolutions);

我不确定如何解决添加0索引值的问题（不使用两个单独的for循环）。谁能帮我吗？非常感谢！！：）

Answer 1

当您找到新的最高值时，您需要清除列表：

＆＃13;

var scores = [60, 50, 58, 54, 54, 58, 50, 52, 54, 48, 69, 34, 55, 51, 52, 44, 51, 69, 64, 66, 55, 52, 44, 18, 41, 53, 55, 61, 51, 44];
var highscore = 0;
var highscoreSolutions = [];
var score;

for (var i = 0; i < scores.length; i++) {
  score = scores[i];
  if (score == highscore) {
    highscore = score;
    highscoreSolutions.push(i);
  } else if (score > highscore) {
    highscore = score;
    // We have a new highest score, so all the values currently in the array
    // need to be removed
    highscoreSolutions = [i];
  }
}

snippet.log(highscore);
snippet.log(highscoreSolutions.join(", "));

＆＃13;

<!-- Script provides the `snippet` object, see http://meta.stackexchange.com/a/242144/134069 -->
<script src="http://tjcrowder.github.io/simple-snippets-console/snippet.js"></script>

＆＃13;

Answer 2

这可能听起来过度设计了你，但是当你似乎在学习JavaScript时，我建议你跳过for次迭代（好吧，你应该知道它们存在并且它们可以用来循环）并学习使用JavaScript使用functional programming范例（a great interactive tutorial for that），因为它会带来更易读，更不容易出错的代码。

问题的解决方案可以使用[].reduce()：

function highest(numbers) {
  return numbers.reduce(function(winner, current, index) {
    if (current > winner.value) {
      return {value: current, indices: [index]};
    } else if (current === winner.value) {
      winner.indices.push(index);
      return winner;
    } else {
      return winner;
    }
  }, {value: Number.NEGATIVE_INFINITY, indices: []});
}

＆＃13;

function highest(numbers) {
  return numbers.reduce(function(winner, current, index) {
    if (current > winner.value) {
      return {value: current, indices: [index]};
    } else if (current === winner.value) {
      winner.indices.push(index);
      return winner;
    } else {
      return winner;
    }
  }, {value: Number.NEGATIVE_INFINITY, indices: []});
}

document.querySelector('button').addEventListener('click', function() {
  var randoms = new Array(100).join(' ').split('').map(function() {return Math.ceil(Math.random() * 100)});
  document.querySelector('#array').innerHTML = JSON.stringify(randoms);
  document.querySelector('#result').innerHTML = JSON.stringify(highest(randoms));
});

＆＃13;

<button>run</button>
<h3>the array</h3>
<pre id="array"></pre>
<h3>the result</h3>
<pre id="result"></pre>

＆＃13;

Answer 3

var scores = [60, 50, 58, 54, 54, 58, 50, 52, 54, 48, 69, 34, 55, 51, 52, 44, 51, 69, 64, 66, 55, 52, 44, 18, 41, 53, 55, 61, 51, 44];

//clone array keeping original as scores, sort the new cloned array, grab the max value
var highscore = scores.slice(0).sort()[scores.length - 1];
var highscoreSolutions = [];

//find occurances of highscore and push to array
for (var i = 0; i < scores.length; i++){
    if (scores[i] == highscore){
        highscoreSolutions.push(i);
    }
}

alert('highscore: ' + highscore + '\nindexes: ' + highscoreSolutions)

您可以使用Array.slice（0）

克隆数组

然后运行sort（）并通过检查长度-1

获取新排序数组的最后一个值

然后迭代循环以找到高分数所在的索引。

用于循环数组迭代问题的JavaScript - 使用一对二循环

3 个答案: