主要想使用下哈希，所以写成了这样
function strLength(arr,h = Object.create(null)){
    arr.forEach(v => h[v] = (h[v] || 0) + 1)
    return Object.keys(h).sort((a, b) => a - b)
}
let n = parseInt(readline());
let arr = [...Array(n)].map(() => readline());
let nubs=strLength(arr)
    nubs.forEach(item=>{
       console.log(item)
    })