[백준] 2579 계단 오르기 - Dynamic Programming / Java

• 문제 링크

2579번: 계단 오르기

 

• 풀이 과정

 

• 풀이 코드

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;

public class Main {

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));

        int n = Integer.parseInt(br.readLine());

        int[] arr = new int[n + 1];
        int[] dp = new int[n + 1];

        for (int i = 1; i <= n; i++)
            arr[i] = Integer.parseInt(br.readLine());

        dp[1] = arr[1];

        for (int i = 2; i <= n; i++) {
            if (i == 2)
                dp[2] = arr[1] + arr[2];
            else if (i == 3)
                dp[3] = Math.max(arr[1], arr[2]) + arr[3];
            else
                dp[i] = Math.max(dp[i - 3] + arr[i - 1], dp[i - 2]) + arr[i];
        }

        bw.write(String.valueOf(dp[n]));
        bw.flush();
    }

}