poj 3628 Bookshelf 2

http://poj.org/problem?id=3628

01背包

#include <cstdio>
#include <iostream>
#include <cstring>
#include <algorithm>
#define maxn 21
#define ll long long
using namespace std;

ll h[maxn];
int n;
ll b;
ll dp[1000004];
ll max1(ll a,ll b)
{
    return a>b?a:b;
}

int main()
{
    while(scanf("%d%lld",&n,&b)!=EOF)
    {
        ll v=0;
        for(int i=1; i<=n; i++)
        {
            scanf("%lld",&h[i]);
            v+=h[i];
        }
        for(int i=1; i<=n; i++)
        {
            for(ll j=v; j>=h[i]; j--)
            {
                dp[j]=max(dp[j-h[i]]+h[i],dp[j]);
            }
        }
        for(ll j=1; j<=v; j++)
        {
            if(dp[j]>=b)
            {
              printf("%lld
",dp[j]-b);
              break;
            }
        }
    }
    return 0;
}