基础算法脚本

标签：脚本 return words currentLength 基础 length 算法 let str

将字符串翻转：

function reverseString(str) {
  //法一：
  /*
  let arr=[];
  for(let i=0;i<str.length;i++){
    arr.unshift(str[i]);
  }
  //console.log(arr);//[ 'o', 'l', 'l', 'e', 'h' ]
  str='';
  for(let i=0;i<arr.length;i++){
    str=str+arr[i];
  }
  //console.log(str);//olleh
  return str;
  */
  //法二：
  let reversedStr = "";
  for (let i = str.length - 1; i >= 0; i--) {
    reversedStr += str[i];
  }
  //法三：
  /* 
  return str
    .split("")
    .reverse()
    .join("");
  */
  return reversedStr;
}
//调用：
console.log(reverseString("hello")); //olleh

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求整数的阶乘：

只有大于或等于零的整数才能计算阶乘，阶乘是所有小于或等于n的正整数的乘积，简写为n!，例如：5！=1 * 2 * 3 * 4 * 5 = 120

function factorialize(num) {
  //法一：
  /*let product = 1;
  for (let i = 2; i <= num; i++) {
    product *= i;
  }
  return product;*/
  //法二：
  /*if (num === 0) {
    return 1;
  }
  return num * factorialize(num - 1); */
  //法三：
  return num < 0 ? 1 :
    new Array(num)
      .fill(undefined)
      .reduce((product, _, index) => product * (index + 1), 1); 
}

//法四：
/*function factorialize(num, factorial = 1) {
  if (num === 0) {
    return factorial;
  } else {
    return factorialize(num - 1, factorial * num);
  }
}*/

console.log(factorialize(5)); //120

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查找字符串中最长的单词，返回其长度：

function findLongestWordLength(str) {
  //法一：
  //return Math.max(...str.split(" ").map(word => word.length));
  //法二：
  //return str.split(' ').reduce(function(longest, word) {return Math.max(longest, word.length)}, 0);
  //法三：
  /*let words = str.split(' ');
  let maxLength = 0;

  for (let i = 0; i < words.length; i++) {
    if (words[i].length > maxLength) {
      maxLength = words[i].length;
    }
  }
  return maxLength;*/
  //法四：
  /*const words = str.split(" ");
  if (words.length == 1) {
    return words[0].length;
  }
  return Math.max(words[0].length,findLongestWordLength(words.slice(1).join(" ")));*/
  //法五：
let longestLength = 0;
let currentLength = 0;
for (let i = 0; i < str.length; i++) {
  if (str[i] === " ") {
    if (currentLength > longestLength) longestLength = currentLength;
    currentLength = 0;
  } else {
    currentLength++;
  }
}
if (currentLength > longestLength) {
  longestLength = currentLength;
}
return longestLength;

}
//调用：
console.log(findLongestWordLength("The quick brown fox jumped over the lazy dog")); //6

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查找数组中最大的数字：

标签：脚本,return,words,currentLength,基础,length,算法,let,str
From： https://www.cnblogs.com/168-h/p/16733607.html