POJ 1456 Supermarket

辣鸡并查集

用并查集记录最近的可行点

#include <iostream>
#include <cstring>
#include <algorithm>
#include <cmath>
#include <cstdio>
using namespace std;
const int MAXN = 100005;
int fa[MAXN], n, ans;
struct good{
	int cost, loc;
	bool operator < (const good & b) const {
		if(cost != b.cost) return cost > b.cost;
		return loc > b.loc;
	}
}a[MAXN];
int find(int x) {
	if(x <= 0) return 0;
	if(fa[x] != x) return fa[x] = find(fa[x]);
	return fa[x];
}
int main() {
	while(cin >> n) {
		ans = 0;
		for(int i = 1; i < MAXN; i++) fa[i] = i;
		for(int i = 1; i <= n; i++) {
			cin >> a[i].cost >> a[i].loc;
		}
		sort(a + 1, a + 1 + n);
		for(int i = 1; i <= n; i++) {
			if(find(a[i].loc)) {
				//cout << a[i].loc << endl;
				ans += a[i].cost;
				fa[fa[a[i].loc]] = fa[a[i].loc] - 1;
			}
		}
		cout << ans << endl;
	}

	return 0;
}