[프로그래머스 JavaScript] Level2 탑

function solution(heights) {
    var answer = [];
    const length = heights.length;
    heights.reverse();    
    
    answer = heights.map((e, i) => {        
        for (let j = i+1; j < length; j++) {
            if (e < heights[j]) {
                return length - j;
            }
        }
        return 0;
    }).reverse();
    
    return answer;
}