题解 | #字符统计#

let line;

function func(line) {
    let rtnVal;
    const arr = line.split(''); 
    const obj = {}; // 哈希map，本质是一个obj
    const res = [...new Set(arr)]; // 去重
    
    // map结构保存k-v
    res.forEach(item => { 
        const count = arr.filter(el => el == item).length; 
        obj[item] = count; 
    }) 
    
    // 数组按照count大小排序
    res.sort((a,b) => { 
        if(obj[a] == obj[b]) { 
            return a.charCodeAt(0) - b.charCodeAt(0); 
        } else { 
            return obj[b] - obj[a];
        } 
    }) 
    rtnVal = res.join('');
    return rtnVal;
}

while (line = readline()) { 
    print(func(line));
}