C++ 未优化版

#include <iostream>
#include <algorithm>

using namespace std;

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

int main()
{
    cin >> n >> m;
    for(int i = 1;i <= n ;i ++) cin >> v[i] >> w[i];

    for(int i = 1;i <= n;i ++)
        for(int j = 0;j <= m;j ++)
        {
            if( j <v[i]) f[i][j] = f[i - 1][j];
            else f[i][j] = max(f[i - 1][j],f[i - 1][j - v[i]] + w[i]);
        }    
    cout << f[n][m] << endl;
    return 0;
}

C++ 优化版

#include <iostream>
#include <algorithm>

using namespace std;

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

int main()
{
    cin >> n >> m;
    for(int i = 1;i <= n;i ++) cin >> v[i] >> w[i];

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

    cout << f[m] << endl;
    return 0;
}

Java优化版

import java.util.Scanner;
import static java.lang.Math.*;

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 nana = new Scanner(System.in);
        n = nana.nextInt();
        m = nana.nextInt();
        for(int i = 1;i <= n;i ++){
            v[i] = nana.nextInt();
            w[i] = nana.nextInt();
        }
        for(int i = 1;i <= n;i ++)
            for(int j = m;j >= v[i];j --)
                f[j] = max(f[j],f[j - v[i]] + w[i]);

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

    }
}