将计数器添加到 javascript 数组的 n 个组合中答案

【问题标题】：add counter to the n combinations of javascript array将计数器添加到 javascript 数组的 n 个组合中
【发布时间】：2020-01-25 20:59:31
【问题描述】：

这个程序应该从数组中输出许多可能的元素组合。我没有做的是在左侧为每个可能的组合添加一个计数器。第一个组合为“001”，第二个组合为“002”，依此类推，直到最后一个。我尝试使用 for 循环和 while-do 以多种方式做到这一点，但任何尝试都是失败的。

function combine(a, b, c) {

  if (b === 0) {
    console.log(three.join(" "));
    return;
  }

  for (var i = c; i <= a.length - b; i++) {
    three[three.length - b] = a[i];
    combine(a, b - 1, i + 1);
  }

}
const vegetables = ["carrot", "tomatoes", "potatoes", "celery", "pepper"];
const three = [];
three.length = 4;

combine(vegetables, three.length, 0);

【问题讨论】：

标签： javascript arrays combinations counter

【解决方案1】：

您可以使用padStart 来生成您要查找的内容。像这样的

const vegetables = ["carrot", "tomatoes", "potatoes", "celery", "pepper"];
const three = [];
three.length = 4;
let counter = 1;
function combine(a, b, c) {
  if (b === 0) {
    const counterForPrint = (counter++).toString().padStart(3, "0");
    console.log(`${counterForPrint} ${three.join(" ")}`);
    return;
  }
  for (let i = c; i <= a.length - b; i++) {
    three[three.length - b] = a[i]; combine(a, b - 1, i + 1);
  }
}

combine(vegetables, three.length, 0);

顺便说一句，您可以使用一些库来生成组合。它使事情变得非常清晰，让您专注于实际逻辑。像这样的

const Combinatorics = require("js-combinatorics");
const vegetables = ["carrot", "tomatoes", "potatoes", "celery", "pepper"];

const possibleCombinations = Combinatorics.permutation(vegetables);
let counter = 1;
possibleCombinations.forEach(element => {
  const counterForPrint = (counter++).toString().padStart(3, "0");
  console.log(`${counterForPrint} ${element}`);
});

【讨论】：