foreach里面的foreach js

Question

Trying to solve this problem and I don't know where my mistake is!

 function findIntersection(strArr) { const arr1 =[strArr[0]]; const arr2 = [strArr[1]]; const finalArr =[]; arr1.forEach(e=>{arr2.forEach(element => { if(element === e){ finalArr.push(e); console.log(true) } })}) } findIntersection(['1, 3, 4, 7, 13', '1, 2, 4, 13, 15']); // => '1,4,13' findIntersection(['1, 3, 9, 10, 17, 18', '1, 4, 9, 10']); // => '1,9,10'

Answer 1

The problem was with how you were modeling the data. The parameter passed in should be an array of two arrays of integers, you had an array of two strings. If you have to work with an array of two strings, you have to extract the two strings and then use String.split() to convert them into arrays.

 function findIntersection(strArr) { const arr1 = strArr[0] const arr2 = strArr[1] const finalArr = []; arr1.forEach(el1 => { arr2.forEach(el2 => { if (el2 === el1) { finalArr.push(el1); } }) }) return finalArr } const res1 = findIntersection([[1, 3, 4, 7, 13], [1, 2, 4, 13, 15]]); // => '1,4,13' const res2 = findIntersection([[1, 3, 9, 10, 17, 18], [1, 4, 9, 10]]); // => '1,9,10' console.log(res1, res2)

Answer 2

You have various mistakes, including not splitting the string into an array, unnecessarily wrapping it in an array, and not returning your finalArr .

function findIntersection(strArr) {
    const arr1 = strArr[0].split(", ");
    const arr2 = strArr[1].split(", ");
    const finalArr = [];
    arr1.forEach(el1 => {
        arr2.forEach(el2 => {
            if (el1 === el2) {
                finalArr.push(el1);
            }
        });
    });
    return finalArr;
}

Alternatively, use a faster solution with sets:

function findIntersection(strArr) {
    const arr1 = new Set(strArr[0].split(", "));
    const arr2 = strArr[1].split(", ");
    return arr2.filter(el => arr1.has(el));
}