Node.js) 백준 10844번 : 쉬운 계단 수

https://www.acmicpc.net/problem/10844

10844번: 쉬운 계단 수

const fs = require('fs');
const input = fs.readFileSync("/dev/stdin").toString().trim();

const N = +input;

let arr = [0,1,1,1,1,1,1,1,1,1];
let cnt = 1;
while(cnt!=N){
    let tempArr = Array(10).fill(0);
    arr.forEach((v,i)=>{
        switch(i){
            case 0:
                tempArr[1]+=v%1000000000;
            break;
            case 1:
            case 2:
            case 3:
            case 4:
            case 5:
            case 6:
            case 7:
            case 8:
                tempArr[i-1]+=v%1000000000;
                tempArr[i+1]+=v%1000000000;
            break;
            case 9:
                tempArr[8]+=v%1000000000;
            break;
        }
    })
    cnt++;
    arr = tempArr;
}
console.log(arr.reduce((r,v)=>{return (r+v)%1000000000},0))