Got it in JS - it's only the nested loops that really hold the core logic. Hope it helps.

function solve(input) {
    let first = input.shift().charCodeAt(0);
    let second = input.shift().charCodeAt(0);
    let skiped = input.shift();
    let array = [];
    let count = 0;
    let g = "";

    for (let i = first; i <= second; i++) {
        for (let j = first; j <= second; j++) {
            for (let k = first; k <= second; k++) {
                let firstLetter = String.fromCharCode(i);
                let secondLetter = String.fromCharCode(j);
                let thirdLetter = String.fromCharCode(k);

                if (firstLetter !== skiped && secondLetter !== skiped && thirdLetter !== skiped) {

                    count++;
                    g += (firstLetter + secondLetter + thirdLetter) + " ";
                    array.push(firstLetter + secondLetter + thirdLetter);
                }
            }
        }
    }

    array.push(count);
    console.log(array.join(' '));
}