Acwing 2. 01背包

题目链接 Acwing 2. 01背包

朴素版01背包

#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 1010;

int n, m;
int v, w;
int f[N][N];

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

优化版01背包

#include <iostream>
#include <cstring>
#include <algorithm>

using namespace std;

const int N = 1010;

int n, m;
int v, w;
int f[N];

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