poj3614 Sunscreen(贪心)

题意：有C头奶牛，L种防晒霜，每头奶牛可以抹的防晒霜为有个范围，为minSPF和maxSPF，每种防晒霜有对应的SPF，问最多可以让多少头奶牛抹上防晒霜。
思路：贪心的策略 ：按照minSPF递减顺序遍历奶牛，对于每头奶牛，遍历所有的防晒霜。在这头奶牛可用的防嗮霜里面取最大的
证明：对于当前奶牛可用的任意两瓶防嗮霜x和y，如果SPF[x]

#include
#include
#include
#include
#include
#include
#include
using namespace std; 

const int MAXN = 2505;

struct Cow{
    int minSPF, maxSPF;
}cows[MAXN];
bool cmp(Cow c1, Cow c2){
    return c1.maxSPF < c2.maxSPF;
}

struct Sunscreen{
    int SPF, num;
}sunscreen[MAXN];

int c, l;

int main()
{
    cin >> c >> l;
    for(int i = 1; i <= c; ++i)
        cin >> cows[i].minSPF >> cows[i].maxSPF;
    for(int i = 1; i <= l; ++i)
        cin >> sunscreen[i].SPF >> sunscreen[i].num;
    sort(cows+1, cows+1+c, cmp);
    int ans = 0;
    for(int i = 1; i <= c; ++i)
    {
        int minn = cows[i].maxSPF;
        int minpos = -1;
        for(int j = 1; j <= l; ++j)
        {
            if(sunscreen[j].SPF <= minn && sunscreen[j].SPF >= cows[i].minSPF && sunscreen[j].num > 0){
                minn = sunscreen[j].SPF;
                minpos = j;
            }
        }
        if(minpos == -1) continue;
        ans++;
        sunscreen[minpos].num--;
    }
    cout << ans <<endl;
    return 0;
}