How to run c++ and javascript client code (hackerrank style) on local machine

I am working on learning C++ and Javascript by solving Hackerrank problems. Right now C++ compiles but when I run it stalls. The same with my JavaScript. I would like to learn to feed in data for test cases like they do on the platform. For example: If I have this code in C++:

#include <string>
#include <cstdio>
#include <iostream>
using namespace std;
vector<string> split_string(string);

// Complete the countApplesAndOranges function below.
void countApplesAndOranges(int s, int t, int a, int b, vector<int> apples, vector<int> oranges) {
    int count_a = 0;
    int count_b = 0;
    for (int i = 0; i < apples.size(); i++){
        // apples[i] += a;
        apples[i] += a;
        if (s <= apples[i] && apples[i] <= t )
            count_a +=1;

        // cout << apples[i] << ;
    }
    // for (auto i: apples)
    //     // cout << i << ' ';

    // cout << endl;    
    for (int i = 0; i < oranges.size(); i++){

        // apples[i] += a;
        oranges[i] += b;
        if (s <= oranges[i] && oranges[i] <= t )
            count_b +=1;
        // cout << oranges[i] << "";
    }
    // for (auto i: oranges)
    //     // cout << i << ' ';

    cout << count_a << endl;
    cout << count_b;



}

int main()
{
    string st_temp;
    getline(cin, st_temp);

    vector<string> st = split_string(st_temp);

    int s = stoi(st[0]);

    int t = stoi(st[1]);

    string ab_temp;
    getline(cin, ab_temp);

    vector<string> ab = split_string(ab_temp);

    int a = stoi(ab[0]);

    int b = stoi(ab[1]);

    string mn_temp;
    getline(cin, mn_temp);

    vector<string> mn = split_string(mn_temp);

    int m = stoi(mn[0]);

    int n = stoi(mn[1]);

    string apples_temp_temp;
    getline(cin, apples_temp_temp);

    vector<string> apples_temp = split_string(apples_temp_temp);

    vector<int> apples(m);

    for (int i = 0; i < m; i++) {
        int apples_item = stoi(apples_temp[i]);

        apples[i] = apples_item;
    }

    string oranges_temp_temp;
    getline(cin, oranges_temp_temp);

    vector<string> oranges_temp = split_string(oranges_temp_temp);

    vector<int> oranges(n);

    for (int i = 0; i < n; i++) {
        int oranges_item = stoi(oranges_temp[i]);

        oranges[i] = oranges_item;
    }

    countApplesAndOranges(s, t, a, b, apples, oranges);

    return 0;
}

vector<string> split_string(string input_string) {
    string::iterator new_end = unique(input_string.begin(), input_string.end(), [] (const char &x, const char &y) {
        return x == y and x == ' ';
    });

    input_string.erase(new_end, input_string.end());

    while (input_string[input_string.length() - 1] == ' ') {
        input_string.pop_back();
    }

    vector<string> splits;
    char delimiter = ' ';

    size_t i = 0;
    size_t pos = input_string.find(delimiter);

    while (pos != string::npos) {
        splits.push_back(input_string.substr(i, pos - i));

        i = pos + 1;
        pos = input_string.find(delimiter, i);
    }

    splits.push_back(input_string.substr(i, min(pos, input_string.length()) - i + 1));

    return splits;
}

How would I go about "feeding" it inputs.

Similarly, for the JavaScript:

'use strict';

process.stdin.resume();
process.stdin.setEncoding('utf-8');

let inputString = '';
let currentLine = 0;

process.stdin.on('data', inputStdin => {
    inputString += inputStdin;
});

process.stdin.on('end', _ => {
    inputString = inputString.replace(/\s*$/, '')
        .split('\n')
        .map(str => str.replace(/\s*$/, ''));

    main();
});

function readLine() {
    return inputString[currentLine++];
}

// Complete the countApplesAndOranges function below.
function countApplesAndOranges(s, t, a, b, apples, oranges) {
    let count_a = 0
    let count_b = 0

    for (let i = 0; i < apples.length; i++){
        apples[i] += a

        if (s <= apples[i] && apples[i] <= t)
            count_a += 1

    }
    for (let i = 0; i < oranges.length; i++){
        oranges[i] += b
        if (s <= oranges[i] && oranges[i] <= t)
            count_b += 1

    }


    console.log(count_a)
    console.log(count_b)
}

function main() {
    const st = readLine().split(' ');

    const s = parseInt(st[0], 10);

    const t = parseInt(st[1], 10);

    const ab = readLine().split(' ');

    const a = parseInt(ab[0], 10);

    const b = parseInt(ab[1], 10);

    const mn = readLine().split(' ');

    const m = parseInt(mn[0], 10);

    const n = parseInt(mn[1], 10);

    const apples = readLine().split(' ').map(applesTemp => parseInt(applesTemp, 10));

    const oranges = readLine().split(' ').map(orangesTemp => parseInt(orangesTemp, 10));

    countApplesAndOranges(s, t, a, b, apples, oranges);
}

I understand I could do this manually - by hardcoding local-variables to main() but I would like to learn about C++ - getline() function as well as JavaScript - process.stdin.

Thank you in advance for the help.