背包问题的记忆化搜索写法

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

using namespace std;

const int N = 1010;

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

int dfs(int curu, int curv) {
    if(f[curu][curv] > 0) return f[curu][curv];
    if(curu == n) return 0;
    
    int res = 0;
    if(curv - v[curu] < 0) res = dfs(curu + 1, curv);
    else {
        res = max(dfs(curu + 1, curv), dfs(curu + 1, curv - v[curu]) + w[curu]);
    }
    
    return f[curu][curv] = res;
}

int main() {
    cin >> n >> m;
    
    for(int i = 0; i < n; i ++ ) cin >> v[i] >> w[i];
    
    cout << dfs(0, m) << endl;
    
    return 0;
}

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

using namespace std;

const int N = 1010;

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

int dfs(int curv) {
    if(f[curv]) return f[curv];
    
    for(int i = 0; i < n; i ++ ) {
        if(curv >= v[i]) {
            f[curv] = max(f[curv], dfs(curv - v[i]) + w[i]);
        }
    }
    
    return f[curv];
}

int main() {
    cin >> n >> m;
    
    for(int i = 0; i < n; i ++ ) cin >> v[i] >> w[i];
    
    cout << dfs(m) << endl;
    
    
    return 0;
}

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

using namespace std;

const int N = 1010;

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

int dfs(int group, int curv) {
    if(f[group][curv]) return f[group][curv];
    if(group > n) return 0;
    
    int res = dfs(group + 1, curv);
    
    for(int i = 0; i < s[group]; i ++ ) {
        if(curv < v[group][i]) continue;
        res = max(res, dfs(group + 1, curv - v[group][i]) + w[group][i]);
    }
    
    return f[group][curv] = res;
}

int main() {
    cin >> n >> m;
    
    for(int i = 0; i < n; i ++ ) {
        cin >> s[i];
        for(int j = 0; j < s[i]; j ++ ) {
            cin >> v[i][j] >> w[i][j];
        }
    }
    
    cout << dfs(0, m) << endl;
    
    return 0;
}