[백준] 2579번 계단 오르기 (silver 3

import java.io.*;
import java.util.*;
public class Main {
	public static void main(String[] args) throws IOException {
		BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		int n=Integer.parseInt(br.readLine());
		long[][] num=new long[n][2];
		num[0][0]=Long.parseLong(br.readLine());
		for(int i=1; i<n; i++){
			int temp=Integer.parseInt(br.readLine());
			if(i==1){
				num[i][1]=temp+num[0][0];
				num[i][0]=temp;
			}
			else{
				num[i][0]=num[i-2][0] > num[i-2][1] ? num[i-2][0]+temp : num[i-2][1]+temp;
				num[i][1]=num[i-1][0]+temp;
			}
		}
		long answer= num[n-1][0] >  num[n-1][1] ? num[n-1][0] : num[n-1][1];
        System.out.print(answer);											
	}				
}