贪心 Codeforces Round #109 (Div. 2) B. Combination

 /*
贪心：按照能选的个数和点数降序排序，当条件不符合就break，水题啊！
*/
#include <cstdio>
#include <algorithm>
#include <cstring>
#include <cmath>
using namespace std;

const int MAXN = 1e3 + 10;
const int INF = 0x3f3f3f3f;
struct Card
{
int a, b;
}card[MAXN];

bool cmp(Card x, Card y)
{
if (x.b == y.b)    return x.a > y.a;
return x.b > y.b;
}

int main(void)        //Codeforces Round #109 (Div. 2) B. Combination
{
//    freopen ("B.in", "r", stdin);

int n;
while (scanf ("%d", &n) == 1)
{
for (int i=1; i<=n; ++i)
{
scanf ("%d%d", &card[i].a, &card[i].b);
}
sort (card+1, card+1+n, cmp);

int ans = 0;    int res = 1;    int cnt = 1;
for (int i=1; i<=n; ++i)
{
res += card[i].b - 1;    ans += card[i].a;
cnt = cnt - 1 + card[i].b;
if (cnt <= 0)    break;
if (res <= 0)    break;
}

printf ("%d\n", ans);
}

return 0;
}