Solution to HackerRank's Strong Password Challenge: https://www.hackerrank.com/challenges/strong-password/problem?isFullScreen=true

strongPassword.js

/*
 * Complete the 'minimumNumber' function below.
 *
 * The function is expected to return an INTEGER.
 * The function accepts following parameters:
 *  1. INTEGER n
 *  2. STRING password
 */

function minimumNumber(n, password) {
    // Return the minimum number of characters to make the password strong
    
    const numbers = "0123456789";
    const lower_case = "abcdefghijklmnopqrstuvwxyz";
    const upper_case = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    const special_characters = "!@#$%^&*()-+";
    
    let numIndicator= false;
    let lowerCaseIndicator = false;
    let upperCaseIndicator = false;
    let regexIndicator = false;
    let count = 0;
    
    for (let i=0; i < n; i++) {
        if(!numIndicator && findChar(numbers, password[i])) {
            count ++;
            numIndicator = true;
        }
        if(!lowerCaseIndicator && findChar(lower_case, password[i])) {
            count++;
            lowerCaseIndicator = true;
        }
        if(!upperCaseIndicator && findChar(upper_case, password[i])) {
            count++;
            upperCaseIndicator = true;
        }
        if(!regexIndicator && findChar(special_characters, password[i])) {
            count++;
            regexIndicator = true;
        }
    }
    
    count = 4 - count;
    
    if(n + count < 6) {
        count = 6 - n;
    }
    
    function findChar(arr, c) {
        const l = arr.length;
        for(let i = 0; i < l; i++) {
            if(c == arr[i]) return true;
        }
        return false;
    }
    
   return count;

}