hdu2546 饭卡 ０１背包

link:http://acm.hdu.edu.cn/showproblem.php?pid=2546

也算一个贪心的想法吧．

先把总钱数减去５，再把价值最大的挑出来．然后用０１背包．最终买下挑出来的那个价值最大的商品．这样的话，我就实现了最终用最少的钱数买了价值最多的商品，剩下钱数当然也是最少了．

#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cctype>
#include <algorithm>
#include <queue>
#include <deque>
#include <queue>
#include <list>
#include <map>
#include <set>
#include <vector>
#include <utility>
#include <functional>
#include <fstream>
#include <iomanip>
#include <sstream>
#include <numeric>
#include <cassert>
#include <ctime>
#include <iterator>
const int INF = 0x3f3f3f3f;
const int dir[8][2] = {{-1,0},{1,0},{0,-1},{0,1},{-1,-1},{-1,1},{1,-1},{1,1}};
using namespace std;
int main(void)
{
    ios::sync_with_stdio(false);
    int n, V;
    int c[1111], f[1111];
    #ifndef ONLINE_JUDGE
    freopen("in.txt", "r", stdin);
    #endif // ONLINE_JUDGE
    while (cin>>n)
    {
        if(!n) break;
        for (int i = 0; i < n; ++i) cin>>c[i];
        cin>>V;
        V-=5;
        if (V<0)
        {
            cout<<V+5<<endl; continue;
        }
        int tmp=-1, Max;
        for (int i = 0; i <n; ++i)
            if(tmp<c[i]) tmp=c[i], Max=i;
        memset(f,0,sizeof(f));
        for (int i=0;i<n;++i)
        {
            if (i==Max) continue;
            for (int v = V; v>=c[i]; --v)
            {
                f[v] = max(f[v], f[v-c[i]]+c[i]);
            }
        }
        cout<<V+5-f[V]-c[Max]<<endl;
    }
    return 0;
}

囧