supermarket [POJ1456]

Posted 2021-03-09 keik

** 算法二：
贪心策略

1. 优先考虑利润大的商品
2. 每个商品，售出的时间越晚越好。

#include <iostream>
#include <algorithm>
using namespace std;

const int N = 10000 + 10;
int n;
typedef pair<int, int> PII;
PII a[N];

int fa[N];
int get(int x)
{
    if (fa[x] == x)
        return x;
    return fa[x] = get(fa[x]);
}
int main()
{
    while (cin >> n)
    {
        int m = 0; int ans = 0;
        for (int i = 1; i <= n; i++)
        {
            cin >> a[i].first >> a[i].second;
            m = max(m, a[i].second);
        }
        sort(a + 1, a + n + 1);
        reverse(a + 1, a + n + 1);

        for (int i = 1; i <= m; i++)
        {
            fa[i] = i;
        }
        
        for (int i = 1; i <= n; i++)
        {
            int day = get(a[i].second);
            if (!day)
                continue;
            ans += a[i].first;
            fa[day] = get(day - 1);
        }
        cout << ans << endl;
    }
}