BOJ - 2056 작업

www.acmicpc.net/problem/2056

2056번: 작업

 

위상정렬 공부다가.. 결국 DP로 처리한다..

위상정렬이 어렵네..

 

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import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.StringTokenizer;

public class BOJ2056 {
    static int N;
    static int[] D;
    public static void main(String[] args) throws IOException {
        System.setIn(new FileInputStream("res/input_boj2056.txt"));
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        long Start = System.currentTimeMillis();
        StringTokenizer st;
        N = Integer.parseInt(br.readLine());
        D = new int[N+1];

        int a, b, c;
        int res = 0;
        for (int i = 1; i <= N ; i++) {
            st = new StringTokenizer(br.readLine());
            c = Integer.parseInt(st.nextToken());
            a = Integer.parseInt(st.nextToken());
            for (int j = 1; j <= a ; j++) {
                b = Integer.parseInt(st.nextToken());
                D[i] = Math.max(D[i], D[b]);
            }
            res = Math.max(res, D[i]+= c);
        }

        System.out.println(res);
    }
}