[JavaScript] 프로그래머스 스킬트리 LEVEL3

function solution(skill, skill_trees) {
    let answer = 0;
    const skillArr = skill.split('');
    
    for (let tree of skill_trees) {
        let idxArr = [];
        let cnt = 0;
        for (let i=0; i<tree.length; i++) {
            if (skillArr.includes(tree[i])) idxArr.push([tree[i], cnt++]);
        }
        
        let flag = true;
        for (let [s, idx] of idxArr) {
            if (s !== skillArr[idx]) {
                flag = false;
                break;
            }
        }
        if (flag) answer++;
    }
    
    return answer;
}

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