题目描述

完全背包

无优化

import java.util.*;
public class Main{

    static int N = 1010;
    static int n, m;
    static int[] v = new int[N];
    static int[] w = new int[N];
    static int[][] f = new int[N][N];

    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        m = sc.nextInt();

        for (int i = 1; i <= n; i ++ ){
            v[i] = sc.nextInt();
            w[i] = sc.nextInt();
        }

        for (int i = 1; i <= n; i ++ ){
           for (int j = 1; j <= m; j ++ ){
                //k表示的是当前物品用几次   k*v[i] <= j去判断能否装的下
                for(int k = 0; k*v[i] <= j ; k++)
                    f[i][j] = Math.max(f[i][j], f[i-1][j-k*v[i]] + k*w[i]);
           }
        }

        System.out.println(f[n][m]);
    }
}

有优化

import java.util.*;
public class Main{

    static int N = 1010;
    static int n, m;
    static int[] v = new int[N];
    static int[] w = new int[N];
    static int[] f = new int[N];

    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        m = sc.nextInt();

        for (int i = 1; i <= n; i ++ ){
            v[i] = sc.nextInt();
            w[i] = sc.nextInt();
        }

        for (int i = 1; i <= n; i ++ ){
           for (int j = v[i]; j <= m; j ++ ){
                f[j] = Math.max(f[j], f[j - v[i]] + w[i]);
           }
        }

        System.out.println(f[m]);
    }
}