[프로그래머스 Level 2] 할인 행사

function solution(want, number, discount) {
    let answer = 0;
 
    let start = 0;
    let end = 9;
    let products = Object.fromEntries(want.map((product, i) => [product, number[i]]));
    let remain = new Set(want);
 
    const put = (product) => {
        products[product] -= 1;
        if(products[product] <= 0) remain.delete(product);
    }
 
    const out = (product) => {
        products[product] += 1;
        if(products[product] > 0) remain.add(product);
    }
 
    for(let i = start; i <= end; i++){
        put(discount[i])
    }
 
    while(end < discount.length){
        if(remain.size === 0){
            answer++;
        }
 
        out(discount[start++]);
        put(discount[++end]);
    }
 
    return answer;
}