记忆化·搜索 求大佬帮助

#include<bits/stdc++.h>
using namespace std;
int f[3505];
int c[3505];
int w[3505];
int t;
bool flag[3505];
int dfs(int kg) {
	int u=0;
	if(f[kg]!=-1)return f[kg];
	for(int i=1; i<=t; i++)
		if(!flag[i])
			if(c[i]<=kg) {
				flag[i]=1;
				u=max(u,dfs(kg-c[i])+w[i]);
				flag[i]=0;
			}
	return f[kg]=u;
}
int main() {
	int m;
	cin>>t>>m;
	memset(f,-1,sizeof(f));
	for(int i=1; i<=t; i++)
		cin>>c[i]>>w[i];
	cout<<dfs(m);
}/*
4 6
1 4
2 6
3 12
2 7*/