01背包问题回溯

1.

#include<iostream>
#define MAX 10000
using namespace std;

//int i,j;
int n,m;//n标志背包容量，m标致物品个数
int result=-9999;
int vis[MAX] = {0};
int w[MAX] = {0};
int v[MAX] = {0};


void dfs(int tw,int tv)
{
    if(tw>n) return;
    for(int i=0;i<m;i++)
    {
        cout<<"i : "<<m<<endl;

        if(vis[i]==0)
        {
            if(tw+w[i]<=n && tv+v[i]>result) result = tv+v[i];
            vis[i] = 1;
            dfs(tw+w[i], tv+v[i]);
            vis[i] = 0;
        }
    }
}
int main()
{
    freopen("C://in.txt","r",stdin);
    scanf("%d,%d",&n,&m);
    for(int j=0;j<m;j++)
    {
        scanf("%d,%d",&w[j],&v[j]);
    }
    dfs(0,0);
    cout<<result;

}
/*
10,5
2,1
3,2
4,5
5,7
8,9
*/

2.

#include<iostream>
#define MAX 10000
using namespace std;

//k标志到第几个物品了
int n,m;//n标志背包容量，m标志物品个数
int result=-9999;
int vis[MAX] = {0};
int w[MAX] = {0};
int v[MAX] = {0};
int c =0;


void dfs(int tw,int tv,int k)
{
    //c++;
    if(k>=m)//数组已经越界
    {
        if(tv>result)
        {
            result = tv;
        }
        return;
    }
    if(tw+w[k]<=n)
    {
        dfs(tw+w[k],tv+v[k],k+1);
        //cout<<c<<endl;
    }
    dfs(tw,tv,k+1);
}
int main()
{
    freopen("C://in.txt","r",stdin);
    scanf("%d,%d",&n,&m);
    for(int j=0;j<m;j++)
    {
        scanf("%d,%d",&w[j],&v[j]);
    }
    dfs(0,0,0);
    cout<<result<<endl;

}
/*
10,5
2,1
3,2
4,5
5,7
8,9
*/