[Java] 백준 7579번 앱 - 배낭 문제 응용

https://www.acmicpc.net/problem/7579

7579번: 앱

배낭 문제의 응용편이다.

기존 문제는

(무게 제한 안넘기기 -> 가치 최대화) 였다면

(메모리 제한 넘기기 -> 코스트 최소화) 여서 발상이 쉽지 않았다.

import java.util.*;
import java.io.*;

public class g3_7579 {
    static FastScanner fs = new FastScanner();
    static PrintWriter pw = new PrintWriter(System.out);
    static int n, m;
    static List<App> apps = new ArrayList<>();
    static int[][] pp;

    public static void main(String[] args) {
        n = fs.nextInt();
        m = fs.nextInt();

        for (int i=0;i<n;i++){
            apps.add(new App(fs.nextInt(), 0));
        }
        for (int i=0;i<n;i++){
            apps.get(i).cost = fs.nextInt();
        }

        int ans = Integer.MAX_VALUE;
        pp = new int[10002][n + 1];
        for (int col=1;col<=n;col++){
            App now = apps.get(col - 1);
            for (int row=1;row<=10001;row++){
                if (now.cost > row - 1){
                    pp[row][col] = pp[row][col - 1];
                }
                else{
                    pp[row][col] = Math.max(pp[row][col - 1], pp[row - now.cost][col - 1] + now.mem);
                }

                if (pp[row][col] >= m){
                    ans = Math.min(ans, row - 1);
                }
            }
        }
        pw.println(ans);
        pw.close();
    }

    static class App {
        int mem, cost;

        public App(int mem, int cost){
            this.mem = mem;
            this.cost = cost;
        }
    }

    // ----------input function----------

    static void sort(int[] a) {
        ArrayList<Integer> L = new ArrayList<>();
        for (int i : a)
            L.add(i);
        Collections.sort(L);
        for (int i = 0; i < a.length; i++)
            a[i] = L.get(i);
    }

    static class FastScanner {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer("");

        String next() {
            while (!st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        int[] readArray(int n) {
            int[] a = new int[n];
            for (int i = 0; i < n; i++)
                a[i] = nextInt();
            return a;
        }

        long nextLong() {
            return Long.parseLong(next());
        }
    }
}