1688: [Usaco2005 Open]Disease Manangement 疾病管理( 枚举 )

我一开始写了个状压dp..然后没有滚动就MLE了...

其实这道题直接暴力就行了... 2^15枚举每个状态, 然后检查每头牛是否能被选中, 这样是O( 2^15*1000 ), 也是和dp一样的时间复杂度....有点贪心的feel

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#include<cstdio>

#include<algorithm>

#include<iostream>

#include<cstring>

 

#define rep(i, n) for(int i = 0; i < n; ++i)

#define clr(x, c) memset(x, c, sizeof(x))

#define b(i) (1 << (i))

 

using namespace std;

 

const int maxn = 1005, maxd = 16;

 

int cow[maxn], lim, n, d;

 

bool jud(int s) {

int tot = 0;

rep(i, d) if(b(i) & s) tot++;

return tot <= lim;

}

 

int main() {

freopen("test.in", "r", stdin);

cin >> n >> d >> lim;

rep(i, n) {

cow[i] = 0;

int t, v;

scanf("%d", &t);

while(t--) {

scanf("%d", &v);

cow[i] |= b(v - 1);

}

}

int tot, ans = 0;

rep(s, b(d)) if(jud(s)) {

tot = 0;

rep(i, n) if((s | cow[i]) == s) tot++;

ans = max(tot, ans);

}

cout << ans << "\n";

return 0;

}

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1688: [Usaco2005 Open]Disease Manangement 疾病管理

Time Limit: 5 Sec  Memory Limit: 64 MB
Submit: 423  Solved: 281
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Description

Alas! A set of D (1 <= D <= 15) diseases (numbered 1..D) is running through the farm. Farmer John would like to milk as many of his N (1 <= N <= 1,000) cows as possible. If the milked cows carry more than K (1 <= K <= D) different diseases among them, then the milk will be too contaminated and will have to be discarded in its entirety. Please help determine the largest number of cows FJ can milk without having to discard the milk.

Input

* Line 1: Three space-separated integers: N, D, and K * Lines 2..N+1: Line i+1 describes the diseases of cow i with a list of 1 or more space-separated integers. The first integer, d_i, is the count of cow i's diseases; the next d_i integers enumerate the actual diseases. Of course, the list is empty if d_i is 0. 有N头牛,它们可能患有D种病,现在从这些牛中选出若干头来,但选出来的牛患病的集合中不过超过K种病.

Output

* Line 1: M, the maximum number of cows which can be milked.

Sample Input

6 3 2
0---------第一头牛患0种病
1 1------第二头牛患一种病,为第一种病.
1 2
1 3
2 2 1
2 2 1

Sample Output

5

OUTPUT DETAILS:

If FJ milks cows 1, 2, 3, 5, and 6, then the milk will have only two
diseases (#1 and #2), which is no greater than K (2).

HINT

Source

Silver