HDU 1171 Big Event in HDU

http://acm.hdu.edu.cn/showproblem.php?pid=1171

01背包 

#include<bits/stdc++.h>
using namespace std;
const int maxn = 1000*100 +100;
int dp[maxn],v[5010];
void init()
{
    memset(dp,0,sizeof(dp));
    memset(v,0,sizeof(v));
}
int main ()
{
    ios::sync_with_stdio(false);
    int n;
    while (cin >> n)
    {
        init();
        if(n<0)
            break;
        int sum =0,size=0;
        for(int i=0;i<n;i++)
        {
            int x,y;
            cin >> x >>y;
            sum+=x*y;
            while(y--)
            {
                v[size++] = x;
            }
        }
        for(int i=0;i<size;i++)
        {
            for(int j=sum/2;j>=v[i];j--)
                dp[j] = max(dp[j],dp[j-v[i]]+v[i]);
        }
        cout<<sum-dp[sum/2]<<" "<<dp[sum/2]<<endl;

    }
}

//多重背包也可以

#include<bits/stdc++.h>
using namespace std;
const int maxn = 1000*100+100;
int dp[maxn],v[maxn],c[maxn];

void init()
{
    memset(dp,0,sizeof(dp));
    memset(v,0,sizeof(v));
    memset(c,0,sizeof(c));
}
int main ()
{
    int n;
    while (~scanf("%d",&n) && n>=0)
    {
        init();
        int sum =0;
        for(int i=1;i<=n;i++)
        {
            scanf("%d %d",&v[i],&c[i]);
            sum+=v[i]*c[i];
        }
        for(int i=1;i<=n;i++)
        {
            if(v[i]*c[i] > sum/2)
            {
                for(int j=v[i];j<=sum/2;j++)
                    dp[j] = max(dp[j],dp[j-v[i]]+v[i]);
            }
            else
            {
                int k=1,t=c[i];
                while (k<t)
                {
                    for(int j=sum/2;j>=k*v[i];j--)
                        dp[j] =max(dp[j],dp[j-v[i]*k]+k*v[i]);
                    t-=k,k*=2;
                }
                for(int j=sum/2;j>=t*v[i];j--)
                    dp[j] = max(dp[j],dp[j-t*v[i]]+t*v[i]);

            }
        }
        printf("%d %d
",sum-dp[sum/2],dp[sum/2]);
    }
}

dp[j] = max(dp[j] ,dp[j- 单个物品的价值] +单个物品的价值)