49adjecency_list.js

let arr = [[1, 2], [1, 3], [1, 4], [2, 1], [2, 3], [2, 5], [3, 4], [4, 2]];

function solution(n, arr) {
    let answer = 0;
    let graph = Array.from(Array(n+1), () => Array());
    let ch = Array.from({ length: n+1 }, () => 0);
    let path = [];

    for (let [a, b] of arr) {
        graph[a].push(b);
    }

    function DFS(v) {
        if (v === n) {
            answer++;
            console.log(path);
        } else {
            for (let i = 0; i <= graph[v].length; i++) {
                if (ch[graph[v][i]]=== 0) {
                    ch[graph[v][i]] = 1;
                    path.push(graph[v][i]);
                    DFS(graph[v][i]);
                    ch[graph[v][i]] = 0;
                    path.pop();
                }
            }
        }
    }

    ch[1] = 1;
    DFS(1);
    return answer;
}

console.log(solution(5, arr));