NYOJ 1107 最高的奖励(贪心+优先队列)

#include <stdio.h>
#include <string.h>
#include <iostream>
#include <queue>
#include <algorithm>

using namespace std;
const int N = 50005;
bool vis[N];
struct Node{
    int day, value;
    friend bool operator < (const Node a, const Node b)
    {
        return a.value > b.value;//value小的优先级高
    }
};

bool cmp(const Node a, const Node b)//二级排序, 先按照天数来排,天数小的在前,相同天数的情况下再按照奖励大小来排,奖励大的在前
{
    if (a.day != b.day)
        return a.day < b.day;
    return a.value > b.value;
}
int n;
Node node[N];
int main()
{
    while (~scanf("%d", &n) && n)
    {
        for (int i = 0; i < n; i++)
        {
            scanf("%d %d", &node[i].day, &node[i].value);

        }
        sort(node, node + n, cmp);
        priority_queue<Node> Q;
        memset(vis, false, sizeof(vis));
        for (int i = 0; i < n; i++)
        {
            if (!vis[node[i].day])//如果这一天没有其它任务占有
            {
                vis[node[i].day] = true;
                Q.push(node[i]);
            }
            else
            {
                if (Q.size() < node[i].day)//如果这一天前面有空闲的天数
                    Q.push(node[i]);
                else
                {
                    Node tmp = Q.top();//将它与最小值比较,如果大于添加到队列中的最小值,就要替换
                    if (tmp.value < node[i].value)
                    {
                        Q.push(node[i]);
                        Q.pop();
                    }
                }
            }
        }
        long long ans = 0;
        while (!Q.empty())
        {
            Node tmp = Q.top();
            Q.pop();
            ans += tmp.value;
        }
        cout << ans << endl;
    }

    return 0;
}