poj3614 Sunscreen

思路：

贪心，对于某个防晒霜，把它分给它能满足的所有的牛中要求最严格的一个（若把所有能满足的区间按照左端点从小到大排序的话，则分给右端点最小（区间最短）的一个）。

实现：

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <queue>
#include <functional>
using namespace std;

struct cow
{
    int minn, maxn;
};

struct lotion
{
    int s, c;
};

cow a[2505];
lotion t[2505];
int C, L;

bool cmp(const cow & c1, const cow & c2)
{
    if (c1.minn != c2.minn)
    {
        return c1.minn < c2.minn;
    }
    return c1.maxn < c2.maxn;
}

bool cmp1(const lotion & l1, const lotion & l2)
{
    return l1.s < l2.s;
}

int main()
{
    cin >> C >> L;
    priority_queue<int, vector<int>, greater<int> > q;
    for (int i = 0; i < C; i++)
    {
        cin >> a[i].minn >> a[i].maxn;
    }
    for (int i = 0; i < L; i++)
    {
        cin >> t[i].s >> t[i].c;
    }
    sort(a, a + C, cmp);
    sort(t, t + L, cmp1);
    int cnt = 0, cur = 0;
    for (int i = 0; i < L; i++)
    {
        while (cur < C && a[cur].minn <= t[i].s)
        {
            q.push(a[cur].maxn);
            cur++;
        }
        while (!q.empty() && t[i].c > 0)
        {
            int tmp = q.top();
            q.pop();
            if (t[i].s <= tmp)
            {
                cnt++;
                t[i].c--;
            }
        }
    }
    cout << cnt << endl;
    return 0;
}