样例

const readline = require('readline')

const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
});


let n = null
let path = [] //所有结果

let st = [] //记录dfs中当前数是否可用

rl.on('line', line => {
    n = Number(line)
})

rl.on('close', line => {
    dfs(0)
})


function dfs(u){
    if(u === n){
        console.log(path.join(' '))
        return
    }

    for(let i = 1; i <= n; i++){
        if(!st[i]){
            path[u] = i
            st[i] = true
            dfs(u+1)
            st[i] = false
        }
    }
}