需要帮助返回字符串中最大的 3 个连续数字 (javascript)

Question

在我的函数中，我被赋予了一串数字作为参数。我需要找到最大的 3 位连续数字并返回它。

function largestThreeDigitNum(numString){
    let largestNumber = 0;
    let largestThreeNumber = 0; 
    for(let i= 0; i<numString.length; ++i){
        if(numString[i] === largestNumber){
            largestThreeNumber = largestNumber++
        }
    }
    return largestThreeNumber; 
}

Answer 1

这是一个返回 3 个最大连续数字的小脚本，希望对您有所帮助

function largestThreeDigitNum(numString) {
  var numbers = [];
  
  // Loop to fill an array with all 3 consecutive numbers
  for (var i = 0; i < numString.length - 2; i++) { 
    numbers.push(numString.slice(i, i + 3));
  }
  numbers.sort() // sort the array from the smallest to the biggest
  return numbers[numbers.length - 1] // return the last item of the array, the biggest one
}
console.log(largestThreeDigitNum("693759936") )

Answer 2

好的，让我们假设您的输入字符串类似于"123 465 789"。您可以将其拆分为空格，仅保留 3 位数字，对其进行排序，取最后三位。

largestThreeDigitNum = numString => numString
                                       .split(" ") // split it over spaces
                                       .filter(n => n.length === 3) // keep only 3 digit numbers
                                       .sort()
                                       .slice(-3) // take the last three
console.log( largestThreeDigitNum("56 456 321 78 987 123 741 2 96 41 58 654") )

Answer 3

这是一种冗长的方法，它试图将问题分解为几个小问题，并用小函数解决这些问题。本质上，我们：

• 将字符串转换为数组
• 将数组拆分为三个块，或尽可能接近三个
• 过滤掉长度不是三个数字的块
• 将 3 个"数字"字符串的块转换为单个数字
• 遍历每个数字，记录最大的数字
• 返回最大的

如果您需要快速的东西，那么这不是最有效的解决方案，最好使用其他方法。但是，如果您有兴趣拥有一个由小的可组合块构建的解决方案，那么这可能对您有好处。

const splitIntoAllChunks = size => array => Object.values(
  array
    .reduce((prev, _, i) => ({
      ...prev,
      [i]: array.slice(i, i + size),
    }), {})
);
  
const splitIntoThrees = splitIntoAllChunks(3);
const isLength = length => array => array.length === length;
const stringArrayToNumber = array => Number(array.join(''));
const getMax = (champ, challenger) => challenger > champ ? challenger : champ;
const example = "184727158129123"
const result = splitIntoThrees(example.split(''))
  .filter(isLength(3))
  .map(stringArrayToNumber)
  .reduce(getMax, 0);
  
console.dir(result);

如果你想使用更像原始解决方案的东西，那么你可以用这样的东西来修复它：

const testData = "1234596789"
function largestThreeDigitNum(numString){
    // this could be passed into the function instead, that way
    // the same code could be used for numbers of different sizes
    let numberSize = 3;
    // we only care about the largest three digit number at any given time
    let largestThreeNumber = 0; 
    // I've changed this to i++ as it's a little more conventional that way
    // I've also setup the loop to stop as soon as it can
    for (let i = 0; i < numString.length - (numberSize - 1); i++){
 
        // find the number for comparison
        const thisNumber = Number(numString.slice(i, i + 3))
        
        // if it's the biggest number, keep track of it
        if(thisNumber > largestThreeNumber){
            largestThreeNumber = thisNumber;
        }
    }
    return largestThreeNumber; 
}
console.dir(largestThreeDigitNum(testData))

Answer 4

你可以使用一个临时数组并检查值。

var array = [101, 102, 103, 307, 308, 309, 211, 215, 227, 249, 479, 480, 481, 901, 902, 635, 636, 637],
    temp = [],
    largest = array.reduce((r, b, i, { [i - 1]: a }) => {
        if (a !== b - 1) {
            temp = [b];
            return r;
        }
        temp.push(b);
        if (temp.length > 3) temp.shift();
        if (temp.length === 3 && (!r || r[0] < temp[0])) return temp.slice();
        return r;
    }, undefined);
console.log(largest);