Question

这是我的片段。我觉得这段代码满足算法，但它没有通过。可能的原因是什么？

function findLongestWord(str, separator) {
    var splitString = str.split(separator);
    for (var i = 1; i <= splitString.length; i++) {
        for (j = 1; j < splitString[i].length; j++) {
            while (j === ' ') {
                return j;
            }
        }
    }
    var greater;
    if (j > greater) {
        greater = j;
    }
    return greater;
}

findLongestWord("The quick brown fox jumped over the lazy dog", ' ');

Answer 1

以下是您的代码，其中包含解释和一些更改以使其正常工作

function findLongestWord(str, separator) {
    var splitString = str.split(separator);

    // Define it as empty string
    var greater = '';

    // Start looping from 0th index upto the length
    for (var i = 0; i < splitString.length; i++) {
        for (j = 0; j < splitString[i].length; j++) {
            // Don't know what this is
            // `j` is the index, i.e. number, it cannot be equal to ` `
            // I guess this is confused with the separator

            // This can be removed without any problem
            while (j === ' ') {
                return j;
            }
            // No use code
        }
        // Here `j` is the length of the word
        // Compare it with the length of greater word
        if (j > greater.length) {
            // Update the greater to current `i` string
            greater = splitString[i];
        }
    }

    // Return greater string.
    return greater;
}

var longestWord = findLongestWord("The quick brown fox jumped over the lazy dog", ' ');
document.body.innerHTML = 'Longest Word: ' + longestWord;

little 优化的相同代码可以重写为

function findLongestWord(str, separator) {
    var splitString = str.split(separator);
    // Define it as empty string
    var greater = '';

    for (var i = 0, len = splitString.length; i < len; i++) {
        if (splitString[i].length > greater.length) {
            // Update the greater to current `i` string
            greater = splitString[i];
        }
    }

    return greater;
}

var longestWord = findLongestWord("The quick brown fox jumped over the lazy dog", ' ');
document.body.innerHTML = 'Longest Word: ' + longestWord;
console.log(longestWord);

使用ES6的解决方案

您可以使用Array#reduce和Arrow functions。对于ES5中的相同代码，请this answer

检查@gurvinder372

str.split(' ').reduce((x, y) => x.length > y.length ? x : y);

function findLongestWord(str, separator) {
    return str.split(' ').reduce((x, y) => x.length > y.length ? x : y);
}

var longestWord = findLongestWord("The quick brown fox jumped over the lazy dog", ' ');
document.body.innerHTML = 'Longest Word: ' + longestWord;
console.log(longestWord);

Answer 2

试试这个fiddle

function findLongestWord(str, separator) {
    return str.split(separator).reduce(function (previousValue, currentValue) {
        return previousValue.length < currentValue.length ? currentValue : previousValue;
    });
}

var longestWord = findLongestWord("The quick brown fox jumped over the lazy dog", ' ');

console.log(longestWord);
document.body.innerHTML = longestWord;

Answer 3

请试试这个：

function findLongestWord(str, separator) {
    var splitString = str.split(separator);  
    var greater = splitString[0];
    for (var i = 1; i < splitString.length; i++) {
        if(greater.length < splitString[i].length){
        greater = splitString[i]
      }
    }  
    return greater;
}

findLongestWord("The quick brown fox jumped over the lazy dog", ' ');

Answer 4

Javascript索引从0开始到（length-1）。在“separator”参数上调用split方法后，单词将存储在 splitString 中，并从0到（length-1）索引。为了找到最长的单词，在开始循环之前，我们可以安全地假设第一个单词是最长的。然后我们可以迭代这些单词来检查是否有任何一个比这长。如果我们找到一个，我们可以更新我们最长的单词。你的内部循环是多余的，代码可以这样写 -

function findLongestWord(str, separator) {
var splitString = str.split(separator);
var greater = splitString[0];
for (var i = 1; i < splitString.length; i++) {
    if(greater.length < splitString[i].length)
    {
        greater = splitString[i];
    }
}
return greater; 
}
findLongestWord("The quick brown fox jumped over the lazy dog", ' ');

N.B。：如果有多个长度最长的单词，使用此算法，您将始终找到第一个从左向右搜索的单词。如果你想要最后一个改变，如果循环中的条件如下 -

if(greater.length <= splitString[i].length)

JavaScript：查找字符串中的最大单词

4 个答案: