动态规划思路--题解 | 【模板】01背包

#include <iostream>
#include <string.h>
using namespace std;

const int N = 1010;
int v[N], w[N];
int dp[N]; 

int main()
{
    // 输入数据
    int n, V;
    cin >> n >> V;
    for (int i = 1; i < n + 1; i++)
        cin >> v[i] >> w[i];

    // 解决第一问
    int ret = 0;
    for (int i = 1; i < n + 1; i++)
        for (int j = V; j >= v[i]; j--)
        {
            dp[j] = max(dp[j], dp[j - v[i]] + w[i]);
            ret = max(ret, dp[j]);
        }
    cout << dp[V] << endl;

    //解决第二问
    // memset(dp, 0, sizeof dp);
    // for (int j = 1; j < V + 1; j++) dp[j] = -1;
    memset(dp, -1, sizeof dp);
    dp[0] = 0;
    for (int i = 1; i < n + 1; i++)
        for (int j = V; j >= v[i]; j--)
            // dp[j] = dp[j];   // 不用写
            if(dp[j - v[i]] != -1)
                dp[j] = max(dp[j], dp[j - v[i]] + w[i]);

    cout << (dp[V] != -1 ? dp[V] : 0) << endl;
    return 0;
}