|洛谷|堆|P3045 [USACO12FEB]牛券Cow Coupons

https://www.luogu.org/problem/show?pid=3045

把c作为关键字放入一个小根堆，在堆里买k个牛，然后再把这个小根堆里的牛放到另一个以p作为关键字的小根堆，买牛直到没钱

注意m要long long

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<queue>
#define ms(i,j) memset(i,j, sizeof i);
using namespace std;
int n,k;
long long m,ans = 0;
struct cow
{
int p,c;
};
struct cmp1
{
bool operator()(cow a, cow b)
{
return a.c>b.c;
}
};
struct cmp2
{
bool operator()(cow a, cow b)
{
return a.p>b.p;
}
};
priority_queue<cow, vector<cow>, cmp1> p1;
priority_queue<cow, vector<cow>, cmp2> p2;
int main()
{
scanf("%d%d%lld", &n, &k ,&m);
for (int i=1;i<=n;i++)
{
cow c;
scanf("%d%d", &c.p, &c.c);
p1.push(c);
}
while (k>0&&!p1.empty())
{
if (m-p1.top().c>=0)
{
m -= p1.top().c; p1.pop(); ans++; k--;
} else break;
}
while (!p1.empty()) {p2.push(p1.top()); p1.pop(); }
while (!p2.empty())
{
if (m-p2.top().p>=0)
{
m -= p2.top().p; p2.pop(); ans++;
} else break;
}
printf("%lld\n", ans);
system("pause");
return 0;
}